MarkSfear

Hi guys,Im looking for some help, im using laptop at the moment coz when i turned on my desktop this morning it prompted me to update my AVG which i did,thats when it went wrong,after asking me to shut it down now will not restart.there is power to the unit but it will not start up. im at a complete loss.any help much appriciated. PS ive tried the ever faithfull "turn it off and back on again" but nothing.