Formatting error? I have brought a maxtor basics external hard drive to transfer my files from a

Question

I have brought a maxtor basics external hard drive to transfer my files from a works computer to - there were no instructions other than plug the thing in - did this and message disc full came up. Rang shop said had to tell the thing whether it was for windows or mac - plugged it in went to my computer found the device and selected format disc as was told to do - now dont get anything at all when i plug the thing in - have i wrecked it - sorry not in the least bit comp lit - as you have probabley gathered - if i have formatted when i shouldnt have is there anything i can do to restore? YP