I started riding on a pinto mare who was pretty much perfect for me, but now someone else rides her. It's werid seeing it, but I guess she's ok with the new rider, which makes me feel ok. If the new owner would be terrible to her and of course, the new owner of 'your' horse was, it'd be bad.
Don't worry about your riding abilities too much. Just ride a lot. It's not like you lost everything, you just have to get it back. Most importantly, enjoy riding, with any horse. Like everyone before me said, not to worry.
Also, getting a trainer is a good idea of EmilyandNikki. Pretty much everyone could use someone looking at how they ride, if 'beginner' or not.
I hope you'll feel confident again soon, and enjoy riding :)