Teeth are gapped after braces!?

[lexie05]

I didnt have really bad teeth just a gap in the front and a small overbite. But I had braces on for 1 1/2 years and they were removed in 2008 and I wore my retainer like the orthodontist told me - first 24 hrs then every night then every other night then once a week and so forth. But in the last year I haven't been wearing it that much at all and my teeth are still straight but the gap on my top front teeth came back. I tried wearing it for 24 hrs again and everynight but within an hour that its off, my teeth are gapped again. I have a clear plastic mold-like retainer.

Is there anything that I can do to get them the way they were? Should I call my orthodonist...would he even help after I done payed him??