How to restore an apple iPhone?

Okay, my mom recently got me an 8gb iPhone. This is my first iPhone & I kind of went a little crazy on the apps without thinking about my storage on my phone. I have about 210mb left & I was wondering if there was a way to kind of erase everything on my phone & start over? If so would I be able to get my contacts, message & pictures? I don't really care about the apps unless I can get some of them back to but it wouldn't make me any difference.

I've also tried to delete the app but it won't give me the storage back it just stays the same. Then I'm like what's the point of deleting it so I re-download it. & it takes more storage. That's why I wanna reset the whole thing.

Also how would I retrieve the apps I paid for? & I just brought an itunes gift card would I still have that money or not?

I hope this makes sense & I hope someone can help me.

Well, you can restore your iPhone to erased everything on your phone. If you still want your contacts, message & pictures but not apps, make a backup for them on iTunes first. Then after iPhone restore, you can restore from the backup to get your contacts, message & pictures back easily.