You've destroyed the partition table by doing what you did. The good thing is that all your files are intact/there,
as long as you do not use any other software or try any other nonsense to try and "fix" or "repair" the situation. Doing so will probably make things worse. Trying to recreate the partition table may cause other problems/issues which could impact your data, so please don't do that.
I strongly recommend you spend a little bit of money (one-time purchase with a lifetime of free updates) and pick up a copy of
GetDataBack for NTFS (assuming the drive is NTFS formatted) or alternately
ZAR. I prefer the former personally, but the latter has useful features too. Both of these programs (but I can attest to the first one for sure) will be able to get
all your files back -- again,
as long as you do nothing else to the drive.
If you go with GetDataBack, the option you want to pick is called "Perform a Quick scan (sudden partition loss, FDisk)". The software has the ability to ignore the partition table and simply look for the NTFS MFT on the drive and go purely off of that for comprehension of file sizes, names, locations, etc.. Trust me, it works, as I've used it many times over for different situations.