I cant open my mozila firefox, videos and msn?

when i try to open this programs and i click the icon nothing happen am not sure which other programs cant be open too, so far only this program i noticed can be opened, other programs like game and internet explorer is ok. i try to run as administration and nothing as well. i try re-download it still cant.. and i try restore to two days ago... still not working.. im not sure what is wrong.