Turned comp off whilst away overnight and when turned back on got no signal message on monitor. Cecked all obvious things, and this has happened before but usually rights itself, only this time lasted 2 days and still same
Any answers please?

Try various combinations as available:

Monitor on different computer

Different computer with monitor

IF cable is detachable from monitor (I've had some that aren't) borrow different cable to try

The problem should follow the malfunctioning component around.

Note that sometimes there's a keyboard combination that can turn a notebook's VGA port on and off (RTFM)

Some equipment will refuse to operate if one of the cooling fans isn't running. Check to see if fan(s) on CPU chip and video accelerator chips are running. May require opening case. Make sure cables and dust accumulation aren't contacting the fan blades. Don't touch the chips or circuit boards unless you know how to eliminate the static potential between your hands and the computer circuitry.

Sometimes a video card can be substituted for a motherboard video output IF the motherboard is equipped with an AGP or PCI Express slot. Might even improve video performance depending on chip set video card is equipped with.