My Macbook Pro has been having an insane amount of problems lately. HELP!

My Macbook Pro has been acting up a TON lately. I've had 15 'kernel panics' in the past two weeks. Also, my screen randomly goes completely black, while I'm in the middle of using the computer... When it does this, it is unresponsive and I have to shut down. Finally, my sound will not work at random times. Every time I've turned on my computer lately, the sound was off (and the volume keys are unresponsive).

The volume issue can generally be solved by rebooting, but the other things are freaking me out. I know literally nothing about this computer, but just want it to be fixed!!!! I will have had it for 3 years in August, but I thought Macs were supposed to last! 😟 I didn't have any problems until now and I at least need this computer to last another year or two until I'm out of college. HELP!!!!