My son studying in DPS , was doing well upto 6th suddenly what has happend donot know , now a days he shows not interest is stud

It usually happens that as the kids grow their priorities, their behavior,attitude towards their surroundings/parents /friends show drastic changes.

They usually show behavioral, emotional, psychological, physical changes too. While your concern as a parent is completely understood, following is a list of things that you can do to make your child feel safe:

1) Make your home a safe base
Adolescent children are exploring life, but need a base to come back to.
Home should be somewhere they feel safe to come back to, where they will be protected, cared for and taken seriously.

2) Mutual support
Parents need to: Agree between themselves about their basic values and rules. Support each other in applying them.
It's difficult for a teenager to respect parents who are always at each other's throats or undermining each other. A common trap is for one parent to ally themselves with their child against the other parent. This usually leads to constant trouble.

3) Listening
Adults need to be a source of advice, sympathy and comfort. A teenager needs to know that his or her parents will not automatically jump down their throat with a judgement, a criticism or routine advice. Listening comes first.

However fast they may be growing up, you are your children's providers and it is reasonable that you should decide what the ground rules are. Whilst adolescents may protest, sensible rules can be the basis for security and agreement. They must be:
Clear, so everybody knows where they stand. Where possible, they should be agreed with the children. Consistent, so everyone sticks to them.

Less restrictive as children become more responsible. You can't (and shouldn't) have rules for everything. While some issues
will not be negotiable, there should be room for bargaining on others. Sanctions, such as grounding or loss of pocket money, will only work if they are established in advance. Don't threaten these if you are not willing to carry them out. Rewards for behaving well are just as important - probably more important, in fact.

5) Managing disagreements
Involve your children in making family rules - like all of us, they are more likely to stick to rules if they can see some logic to them and have helped to make them. If a teenager is reluctant to discuss rules for him or herself, they may still do this if they can see that it might be helpful for younger brothers or sisters. If they don't want to get involved, they will just have to put up with the rules you decide on.

Parents should pick their battles. A lot of things adolescents do are irritating (as you probably irritate them), but not all are worth an argument. It's usually better to spend time on praising good decisions or behaviour. Most annoying habits will burn themselves out once parents stop reacting to them.

6) Don't use corporal (physical) punishment
Although it is now viewed as unhelpful, many people still occasionally smack younger children. If you do this with adolescent children: You create the impression that violence is an acceptable way to solve difficulties. This means that they are more likely to grow up to use violence as adults. You can get stuck in a cycle of violence - you hit them, they hit you back
(because they are now big enough), you hit them again and so on.

7) Set the example
Although they are becoming more independent, your children will still learn a lot about how to behave from you. If you don't want them to swear, don't swear yourself. If you don't want them to get drunk, don't get drunk yourself. If you don't want them to be violent, don't use violence yourself. If you want them to be kind and generous to other people ... try to be like this yourself. "Do as I say, not as I do" just won't work.

8) Gratitude
Don't worry if your children aren't as grateful as you' like. It's great if they are, but they may not be until they have children of their own and realise how demanding it can be. When all else fails - Getting Help

Sometimes, all of this may not be enough and you (or your child) may be unable to cope. Worries about the physical changes of adolescence - are they too early, too late or ever going to happen - or about relationships can be discussed with the family doctor.

If there is violence in your family -  children hitting each other, parents hitting children or children hitting parents - ask for help. When problems arise at school, obviously teachers may be a useful source of information. The teacher may suggest that an educational psychologist becomes involved. Psychologists can find out if there are any particular problems with learning, but can also offer counselling if relationships are the issue.

Adolescents who experience turmoil or distress for more than a few months - persistent depression, anxiety, serious eating disorders or difficult behaviour - generally require outside help. Counselling agencies may be suitable if things have not gone too far. They exist for young people and for parents and some contact addresses are listed below.

Hope this helps.