Do orthodontists still have moulds from previous appointments that I can use?

Hi Yaser,
First off - don't panic. This sort of thing happens a lot! I would contact the dentist/ orthodontist who you visited for tooth straightening urgently. All teeth move, sometimes very gradually, but the longer you leave it the more hassle and cost it will be to realign things again.
They should have a record of the exact position of your teeth at the end of treatment - either a physical model or sometimes a digital 3D scan.
Sometimes by just wearing the new retainer a few days daytime and night time (removed for eating/drinking!) can reposition your teeth progressively back to the 'end of treatment' position. This is a bit like how Invisalign works. Otherwise, if there has been too much drift you might need braces again. So if I were you I'd hurry! :)

Best wishes
Dr Zak Kara