were you trying to get to safe mode in Windows using F8 ?
what version of Windows ?
what laptop model ?
for most modern Dell's F12 before Windows loads (bios startup messages enabled ?) may get you into the 'select boot device menu'
(including:- hard disk, optical drive, usb device, pxe network, recovery partition)
You should got to www.dell.com and download the user guide for the exact model Dell laptop you have
If you go to recovery partition & run system recovery you will probably format hard disk & lose all data so backup anything important first.