how would i go about fixing my bike?

[wonderfulman25]

my bike has a big problem. my friend crashed it once and its never been the same again. whenever i ride the bike, the grears keep grinding. like when i pedal halfway, the gears make a cranking sound and the bike does not progress in distance. the problem is worse when i try going uphill. the brakes are broken as well. the left hand brake functions minimally, and the right hand brake does not work at all. im really frustrated. i need a working bike. my college campus is too big to walk around. it would be too big of a hassle to walk. if anyone knows what the problem is with my bike, and how to fix it, or where to go to fix it. that would be great. thanks!