Files missing from external hard drive but still taking up space

i was copying some files into my external HDD, into a folder called, "ABCDE". a few days later, when i plugged in the HDD into my laptop again, that whole folder was gone, along with alot of the other files. some of the files can still be seen. however, i was sure i did not somewhat accidentally delete the files, as the stuff visiblr to me on the HDD is only 28 GB or so, and when i clicked on "properties" for the HDD, it states that 240 GB was used. I tried recreating the folder "ABCDE" again so as to re-copy my files in, but Windows said a folder with "ABCDE" already existed, and asked if I wanted to merge the two folders together, although Windows search results on the HDD came out with no results. clicking on "Merge" did nothing at all, there was still no "ABCDE" folder. I have tried clicking on the "view hidden folders" option, and $RECYCLE.BIN and $AVG. turned up, (i did a stupid thing to delete $AVG. in a rash moment) and the next time i plugged my HDD into my laptop, an additional RECYCLER folder popped up. i switched off the hidden folders option and $RECYCLE.BIN was still there, and still is now. thinking it may have been a virus, I scanned using McAfee, and McAfee was actually scanning files that I had in my HDD, but cannot be seen by me, and cannot be searched by Windows. How do I solve this problem?

@ praveen, yeah its true that i can see the files when i plug it onto another computer (windows). however, the files appear as shortcuts to the computer's system32 location. the files can still be opened and works fine though. how do i solve this then?