It happened 2 days ago and I still couldn't recover from the shock. My elder sister was getting married and there was a celebration in a club for that reason. All rooms in our house packed up with guests in our house so people had to dress themselves at some other place. I and my 2 little cousins and my 2 friends went to aunts house for changing. Since there was not enough place all can't get together. So I was myself outside and guarding the door. Since it was already late I had to hurry and so I pushed the main door with my hands and was changing outside in hall room. I was so sure that there could be no one there since I thought no one can even think of going to aunts house at that point of time . As soon as I dropped my clothes. The grooms(sister's husband's) own brother pushed the main door. I was busy in changing and so I couldn't stop him from opening... and he saw me in that state. He kind of stared at me for nearly 3 seconds and then said " Sorry " and closed the door back . I was so embarrassed that I was in tears and somehow managed to escape.
Needless to say I couldn't enjoy the entire marriage party and is still shocked.
My sisters husband's brother read in same year in college with me . He came as a guest to our house. We have respect for each other but nothing more than that. I cannot get the matter over and is still shocked. Last day when I met him in college I can feel that his way of giving me respect has changed. He was trying to speak to me regarding studies but I cannot give a single response and am trying to avoid any eye contact with him . He started smiling after I didn't replied . I feel I lost myself respect even though its an accident.

I don't know what's wrong but he gives a weird smile on seeing me after this incident.He was not like this before.
I cannot concentrate on my studies because every time I remember the sceene and his way of staring I feel very bad. My internal exams are approaching and I still couldn't get over the shock . Need some sensible advice.

Just about everyone gets walked in on, or walks in on someone elsecat some time or another. It sounds like this is more seriius in your culture than mine... I would have broken the tension with a joke but it seems yiu are too upset for that. Perhaps if you see him alone you can just say, "I'm very embarassed by what happened but know it was accidental. Thanks for being a gentleman and not saying anything to anyone." Hopefully he will say to forget about it,and withbtge air cleared, you can move on.

If you can't speak of it, that's OK too. Just pretend it never happened and tge discomfort will go away in time.