Gear cable disconnected from gear shifter

[Thatkidnoonelikes]

So I just got a new BTWIN Original 5 and i'm the kind of kid that is sort of reckless with my bike my parents might say. I power up curbs i do wheelies i jump off at high speeds, stuff like that. Well one night i was riding through town and suddenly the chain came off and the gear cable just came out of the gear shifter. Someone stopped to help me with the chain but didn't know how to fix the cable and since he was french i didn't understand him so i went along my merry way. I had been experiencing some issues before this though also. When i would shift to the highest gear, it wouldn't switch and it would make a wierd grinding noise. Now since the incident i can't switch gears and the chain comes off often. Please help

-That kid that no one cares about

(p.s. here is an imgur of some snapshots i took of the cord and the shifter)
http://imgur.com/a/mSyMO

[RBurrelli]

This calls for a trip to the local bike shop most likely. Is there one in your area?

[nfmisso]

This should help:
http://bikeride.com/adjust-rear-derailleur/

get the right tools for the job.