Hello, Welcome To JustAnswer Thanks & Regards Sibu

try the following steps

1. Make sure the computer is turned off ("Shut-down" from the Windows Start menu)
2. Remove any peripherals such an external mouse, keyboard, monitor, USB flash drive etc.
3. Make sure the AC Adapter is plugged in and working.
4. Press and hold down the 0 (zero) key on the keyboard while powering on the computer. Release it when the recovery warning screen appears.
5. If the recovery process offers a choice of Operating Systems, select the appropriate one for you.
6. A warning screen appears, stating that when the recovery is executed all data will be deleted and rewritten.
7. Click Yes to continue.
8. When the Toshiba Recovery Wizard opens select "Recovery of Factory Software" or the appropriate option for your needs.
9. Continue to follow the directions restarting as necessary.

ok

then you need recovery disk to do factory restore

yes zero method should work ,if it snot working then the internal recovery partition on hard disk is corrupt

you need to order recovery disk

https://www.csd.toshiba.com/cgi-bin/tais/support/jsp/serviceUnitVerification.jsp?orderType=SFF

you can order from above

Most welcome ...

and good luck

Have A Nice holidays ahead

bye