I've Installed The Wrong Drivers On My Dell PC And It's Now Unusable. Any Ideas What I Can Do?

This kind of situation does occur sometimes, but its not  something to be scared of. All you have to do is to format the active partition and reinstall the window. When you will reinstall the window it will automatically detect the driver type and will install its built in generic drivers. Since all the drives assembled in PC's are plug and play devices , the  window will detect them and will install its generic/universal drivers for those devices. Then later on when you are done with reinstalling with the windows. Go for the original drivers, install them and I hope this will make your Dell PC work.

But if the problem persists then all you have to do is to log on to the Dell's website i.e. www.dell.com and go to FAQ section and put your problem in the form of question or you can email them your problem and you can ask for the solution. They will guide you how to fix that problem. Their technical experts will handle this problem effectively and can rectify it. If you have a local Dell vendor near by you, then you can take your PC to this place and ask him to fix it.

Why is it unusable?  What error messages have you been given?  What are the drivers for?

My guess is that installing the wrong drivers should not make your computer unusable, but I guess if that's the situation it is in now, then you should probably restore the setting via some backup software programs, or hard drive backups, or maybe just formatting your computer and start all over again.  It is hard to give advice without more information.