Hi all... I am new having only played a couple weeks. I read that you can level up archery by having Faendal train you then pick pocket your money back. Well I tried this and got caught so I ended up defending myself and killing Faendal.
I did this in his house and when exiting the town folk are there to kill me. Which they did then I quit game. Can I take this back or how to rectify this? Thanks!

You reload the game I guess.

Don't kill people in cities. You do that, the rest of the people will attack you.
You better reload to a savegame before killing Faendal.

If you want Faendal back, reload the last save before you had to kill him.

If you're just worried about the rest of the town being after you, then get out of town and stay out for a few days. Find a Whiterun guard who doesn't go hostile on sight and pay your bounty for murder (if you have one) or do your time in jail. Clear your name and give Faendal's neighbors time to get over it, go back to Riverwood and see what happens.

Oh that's brutal. My only hope is that I quit the game before it had a chance to auto save.

If you don't have an earlier save, you can follow Lyn's advice: stay out of town until people get over it and find a guard to clear your name

That's not how you use the level-up trick, incidentally. ^^ What you do, instead, is this:

Spoiler

1. Help Faendal by making Camilla Valerius hate Sven. You can do this either by taking Faendal's fake letter to Camilla and lying about it being from Sven, or by taking Sven's fake letter to her and telling the truth.
2. This will allow you to get Faendal as a follower. Have him follow you.
3. Do a training cycle (up to 5 skill levels per character level) with him.
4. "Trade items" with him, and take your gold out of his inventory.
5. This works with ANY NPC that is both a skill trainer and can be a follower.

Happy archering!

For future reference, you want to get Faendal as a follower first. Then you can just take the gold back when you give him things to carry. It's not pickpocketing then.