I assume you should have said.....
How format my Sony 4GB flash drive
how can find the drivers to format my Sony flash disk
No drivers are required for a flash drive - generic drivers that are built into Windows are used.
If you can access the flash drive's drive letter fine in My Computer or Windows Explorer, RIGHT clck on the drive letter for the flash drive, choose Forrmat.
If you cannot see the drive letter for the flash drive in My Computer or Windows Explorer, you CANNOT format it.
Go to Start - Run - type: diskmgmt.msc , press Enter
Scroll down the resulting screen and look for a Removable drive with a ~ 4gb total size (it will be a bit smaller than that) stated at the left side of a rectangular box that shows the space on the drive.
If you DO NOT see that, the computer is NOT detecting the drive at all.
Try pluggeing it into a DIFFERENT USB port, then go to Start - Run - type: diskmgmt.msc , press Enter again to see if it shows up there.
If the rectangular box for the Removable ~ 4 gb drive shows RAW or unallocated, data on the drive has been DAMAGED.
You CANNOT fomat the drive if you see that.
If you are NOT concerned about whatever data was on the drive previously, if you delete the partition on the drive and make a new one, the flash drive will be usable again andwill; show up in My Computer or Windows Explorer.
However, you CANNOT delete the partition on the drive in Windows due to Microsoft's defaults. There may be programs on the web you can use to do that, however most programs on the web can only format the drive - they can't format the drive if it doesn't show up in MyComputer or Windows Explorer, or delete the existing partition and then format it.
You can use certain programs to repair that data damage, then whatever data it had on it previously will probably be visible again, and the flash drive will then show up in My Computer or Windows Explorer.
Troubleshooting USB device problems including for flash drives, external drives, external memory card readers.
See Response 1:
See response 2 regarding how you use Safely Remove Hardware:
See response 2 regarding examples of which programs you could try to use to repair the data damage: