system setup program

as i was messing around (for reasons i wont go into) i got into the system setup program, at which point i went into boot config and reset my config data, or as i understand it cleared nvram and restarted the system.i also managed to enable the quick boot function. i would like to set this back but can no longer access this setup prog by pressing "del" at the dell screen. since i have done this my sreen looks terrible, it looks like it has poor resolution and everything is too large for the screen. i'm not very computer savvy, please help if you can.