If the SSD is properly mounted, and the netbook wasn't dropped or something, then the SSD is the most likely failure point. As for replacement...
The Mini 9 uses special "Mini 9" SSDs. You can try searching for "mini pcie ssd" or "50mm mini pcie ssd pata", but it's very important that the drive description states that it's for a Mini 9 (or the sister model, the Vostro A90).
Asus netbooks (and others) use "Mini PCIe" SSDs as well, but they're different sizes and interfaces. Some can work in the Mini 9, but only if you mod the 9 (search for "70mm SSD Mini 9" for more info).
STEC makes the OEM drives. RunCore or a 2nd gen SuperTalent (GFDL suffix on the model number) seem to be the best aftermarket options.
Good luck.