Partition disappeared - need to recover files

I left my computer downloading while I went out and when I came back, I found an error screen. This has happened often since I "upgraded" to a one gb DIMM of Ultra memory and *appears* to be a temp problem with the memory on the board and the error msgs. vary quite a bit. This is an issue I want to solve at some point soon, but it's not as important as another problem.

When I rebooted, my download hard drive wouldn't show even its name and Windows XP told me that the drive needed formatting. Can anyone tell me some programs that will access the drive and fix the problems? Easy Recovery Pro only accesses 120 something gbs of the 160 gb hd and wouldn't recover enough of the files to suit me and no other program I found would access the data sufficiently.

This too, has happened before and *sometimes* I could disconnect the drive and reconnect and the drive would get recognized and Partition Magic would "fix errors" on the drive. Other times, I could, with some difficulty move files from the drive. Recognition of the drive was inconsistent, but this time, I've not been able to get it recognized at all.

Any help would be greatly appreciated.

ok try recovery expert from acronis, i recently deleted partition by accident from the disk management, and this utility saved my precious data

GetDataBack works great and I think you will be pleased by the results.

Thanks zombie could have used that a few months ago though.

i found partition table doctor maybe help you.
see:

http://www.google.com/search?hl=en&q=partition+table+doctor