Are my Links still Valid?!

Hey Guys,

Just recently had to have my Magento website re-installed correctly, as developer said configuration wasn't correct the first time around. The website is back up and running, but now I've totally lost my place in Google for most of my key words. ( Page 1 to 9 for example). I've build good links so far to get to the first page, but will Google recognize those links, and place me back up to the first page?! Also, have needed to upgrade my server, as I'm not out of disc space, so could that have affected my ranking I wonder?!

I'm a little stressed tonight

You should take care that you use the same URL's for the same content. Otherwise, they will just point to your 404-page.
If this is not the case, you may still redirect the old URL's to the new ones via htaccess.