all you need is to write the first bytes of your drive to the following
0000000: 4641 5458 da45 c94e 2000 0000 0100 0000 FATX.E.N .......
0000010: 0000 ffff ffff ffff ffff ffff ffff ffff ................
then all ffff .....
.......
0001000: f8ff ffff 0000 0000 0000 0000 0000 0000 ................
many tools can do that , or you can write a 10-line c code to do that
