|You really haven't provided enough info. All we know is you have an HP desktop & it's not sending a signal to the monitor. Please post the model & model number.|
Had the PC been working properly up until this problem started or were you having other issues prior to this happening? When you attempt to boot, are the fans spinning up & LEDs lighting up on the case? Are you hearing any beeps? Was the computer recently moved & possibly something became dislodged in the process? or maybe something was reconnected incorrectly?