Vostro 3750 unable to use F8 key

You'll need a Windows boot disc to do the restore.  If the recovery partition is still there, see here:

http://smsoftdev-solutions.blogspot.com/2009/03/how-to-restore-dell-factory-image-when.html

If not, a manual reinstall is the only way.

Was the hard drive ever repartitioned, or was a manual repair or reinstall done?   Any of these will break the Dell recovery boot sector.

Hi thanks for the advice but I want to find out why the F8 key will not work, it used to work but not now and I need to know why

There is a utility on the hard drive that will let you make a set of backup discs - probably Dell DataSafe.  You'll want to do that if the F8 trip doesn't bring up the factory (NOT System, which is a separate issue) restore.

No the hard drive has not been altered in any way. I do believe to recovery partition is there and not corrupt. Also I want to use the F8 key then I can do a factory restore or just restore to an early time if windows fails to boot

PS it did work in the past so something must have altered but I don't know what

Ensure that you are tapping F8 repeatedly as in here:

Hi natakuc4 Thanks for the link to the video that's exactly what I am trying to do. and yes I am taping the F8 key repeatedly but it just loads into windows. I must have disabled the F8 key somehow Thanks again

Your Fn key may be set to multimedia as a default opposed to the function keys. I'm not sure how things are setup in your model but try to follow the instructions here:

http://dellwindowsreinstallationguide.com/ensure-you-have-the-correct-sata-configuration-in-the-bios-setup-for-your-configuration/function-keys/

Alternatively hold down Fn while tapping F8.

Hi again Natakuc4 I have tried had a look in the BIOS and it is set to Function Keys first and I have tried holding down the Fn key and tapping the F8 key when booting but it still will not work. Thank for you advice