With out a Windows CD it much harder to recover from this problem. At this point I suggest you take the PC to a repair shop. But, first you can buy a USB hard drive adapter - remove the hard drive from the desktop and put it in the adapter.
Plug the adapter into another computer and copy the data files you need. You will need to know what type hard drive you have IDE or SATA, to determine the adapter type. I have a temporary type adapter that is just wires with out a case. It functions with both IDE and SATA drives.
Tell you daughter it was her job to back-up her data to an external device or CD. She should never assume that the hardware will work when she needs it. My daughter always has a copy on the hard disk and one on a flash drive (thumb drive) while she is working on a paper. And we back-up all her data to CDs every month. Another way to save work in progress is the email herself a copy every hour to two.