Why messages posted on my wall disappear , I read a message on my friends wall a day before , than next day it is disappeared.. May I know where I can find them back to read?

Normally how Long does it take for a profile picture to get updated? I have uploaded a image for my profile 5 days ago and yet it is not updated...how long it could take more?..ps.. I have uploaded in jpeg format..Size less than 200kb

Thanks for reply..Yes I can still view their profile, I receive msgs from them..