Deleting from the hard drive removed the files from my external hard drive?

Hi!!

Wonder if anyone can help, i did a software restore on my mac mini cus the usbs screwed up..i backed up all my files on an external hard drive and did the restore, i put all my files back on the computer after it had finished but decided it was taking up loads of space on my mac hard drive..when i deleted the files from the computer it also deleted them from the external hard drive..

but.... my back up folder on the external says it still has 69gb worth of stuff in it like it did before the deleting, but everything in the folder only actually comes to 8gb, except one new folder thats been created named 'net', it wont calculate the size but must be the reason for the back up folder to still say its got 69gb in it?

before i deleted these files i was playing with some of the application support etc getting my old setting sback, dont know if this did anything?

If anyone can help it would be ace cus i have important files deleted that i really need!!! Hope that all made sense?

I have a Mac mini core 2 duo 2.0 ghz superdrive, with leopard

Thanks

Ben