I recently got F1 visa, but I won't be able to attend college due to family issues. My question is what will happen to my B1/B2 visa? Is it revoked because I got F1 or is it still valid?
In general the US allows you to have multiple visas of different types simultaneously (and in some circumstances, even multiple of the same type), so I would expect both of your visas to still be valid.
However there is a sure-fire way to tell - simply look at your older visa. If the old visa was canceled when your new one was issued, they will have stamped the old one with a large "Cancelled Without Prejudice" stamp. If this stamp doesn't exist on the visa, then it's still valid.
(Obviously I'm presuming that the old visa has not expired/etc)
Both visas are allowed to exist separately, you just need to state your intent of travel truthfully when you enter the United States and you can use whichever visa is more appropriate.