Failure to boot PXE 061 is a BIOS message that indicates 2 things: 1.System failed to boot to the hard drive
2.System failed to boot to a network connection
The apparent problem is failure to boot to the hard disk. If the system was running yesterday and there have been no hardware changes to the system, then most likely failures are: 1.HDD failure (Replace the HDD, reinstall OS and applications) I hope you have information backed up.
2.HDD not being detected by the motherboard due to connection issue (Remove HDD and reseat it, then see if seen in BIOS) If no change replace hard drive, if new drive not seen, replace motherboard