If the files are not in your bridge directory look in the trash. If not there you can retrieve from card if you have not overwitten files with new images. Look on the web for a product that will find deleted files on SD card.
It is best if you format your card in the camera rather than deleting images on the card. Mimizes potential errors in bad spots on card.
What to do?? Is there any way to get my files back from Bridge? (and if not, would anyone maybe know whether there's a way to get them back from my Nikon D90?)
I agree with Curt, check the trash and find recovery software for your CF card a.s.a.p.
Don't do anything with the card before trying to use recovery software on it. The main vendors like Sandisk and Lexar offer those online, just do some research.
And it will not help you now but in future it will. Always use a card reader to import files (this avoids the possibility to accidentally wright data to the camera. Never delete files from card before you have checked they have been imported correctly and select some thumbs to judge if the previews are good.
Then be sure to have a proper back up of those files and only then delete the files from the card using it in camera with the camera software option to format the card. This keeps the card clean and long term usable in a reliable way.
And don't panic, it is like it is and in the baddest situation you lose some photographs. That is not good and it will feel like a disaster but after one sleepless night you will find out that is all there is. Accidents happen and as long as you learned your lesson for the rest of your live no one will blame you forever
I learned this lesson the hard way twice in 30 years of photography. Once with being careless developing a film in the analog years and once with digital (in 2001, there was a lot of mystery back then about CF cards and how to handle them) by not proper removing the card from the system before I had copied them. And back then it was very hard to find recovery software or even know you could recover them...