How do i reset the bios for Fujitsu Amilo Pro v3545

Im not sure what you understand by reset ..but if you want them to the original functions and settings ..you should go to bios by pressing F2 on start ..and in there ..look for the line when it says ...press F.... to load optimal factory defaults..Press the indicated key ..(f7 or f9 or f5 ) and it will default itself ..
what you should be looking for is not to load the ahci function for hard disk again if it was disabled...cause the operation system will not be load and hard disk not seen on boot without the ahci driver unless the operation system was installed with it in the first place ..If it makes troubles on boot..and seam not to load windows..go back to windows and under the hard disk settings or in the main settings look for ahci function and disable it and select sata as ide or ide compatible ..and save changes with F10 and restart ..This should make it functional if this was the issue ..and all other setting will be on factory optimal ..