Right now, please do not run any Check Disk operation.
If you have important data to recover, that should be your first priority.
You said that you ran Partition Wizard. What exactly did you do with it?
Did you try Partition Recovery Wizard in it?
If you did not, then do as follows.
Plug-in your external drive and check it in Windows Disk Management. If it appears as RAW
, then run Partition Wizard and follow the process under the heading Recovery with Partition Wizard: SanDisk Cruzer Blade 16GB
in the thread Recover a flash drive turned RAW – Partition Wizard and TestDisk.
Check whether you can recover the partition and gain access to the disk.