Restore to Factory Settings (Laptop)

I have a Toshiba laptop here. I have backup-ed all the files I needed. The onky remaining step is now restoring it to factory settings. I have tried pressing "0" key when turning on the laptop and repeatedly hit "0" key until the Toshiba logo disappears. However, it did not do anything and instead, the laptop comes with a "Starting Windows" screen and proceeds to desktop.

Please do help :) If you need extra information regarding my laptop code(s), please tell me where to find them and I'll look it up!

Additional info: Have I deleted my Disk Partition or something? How can I check this? I know that it is required or something....

Oh, be patient with me, because I seriously have no knowledge regarding Windows AT ALL.

Becayse I gfigured I have too many errors, e.g.: Failing to download Windows Update, extreme poor performances compared to other computers with the same specification as mine, constant lagging, troubleshooting problems, etc. Emm, I'll fill the system specification out, but I don't understand some things....

My antivirus is still Avast.

Ok, I removed all peripherals, but it still doesn't work and instead, proceeds to Desktop.

I'll try looking for it! :) Please be patient XD Oh, also, I tried filling the system spec, but I was unable to fill some out since I don't know where I could get the remaining info.

Nope, no installation CD, only a "BARAA100V2 ADSL2/2 + Ethernet router" CD here in my laptop bag.