PC Boot Problem

Well battery installed and now won't boot at all .
Gets to a stage where it states BOOTMGR missing press ctrl alt del to restart.
Doing that jst returns you to the same message.!!. Also tried with system disc in DVD drive and get same message.
Any ideas, looking like it may have to take atrip down the PC mender, or a new PC and hopefully get a windows easy transfer made from the old HD.

Might have found the problem.
After finally getting it back up and running it has been turning off and on as per normal for a few days. Then today my daughter picked up the wireless mouse when the PC was off and it turned itself on? but not the monitor as per original problem. Went back into the BIOS and changed the power settings to disable any turn on via USB device or PCI card etc. I suspect there is an issue with the wireless mouse and keyboard.
I shall let you know.