Model 635 Singer

[vampiress92.livejournal.com]

Hey! I've been staying with my Grandmother for a while, and have been using her machine for a bit of light sewing. I stitched some fabric onto some jeans using the thread and bobbin already in the machine. Partway into a new project my bobbin ran out of thread. No problem, right? After a few accidents (I suck at winding a bobbin!), I got the hang of it, and wound 3. Well, I go to start sewing, and put it in, and start sewing. It tries to sew, but about four "stitches" in, the needle gets stuck, and when you pull the fabric up, you see a tangle of the needle thread going into the machine, and the needle thread wrapped around the bobbin. The bobbin just sits there O.O
So, um, sorry for the text-only, but what do I do? Its a Singer Model 635.
I've changed the bobbin, re-threaded the machine, tried to clean it, and changed the needle. Help!

EDIT: me and my grandmother played with it for a bit, and got it fixed! I'm still not quite sure what i was doing wrong though, lol. Thanks for the replies!