Hello,
I faced a similar problem with my brother's laptop which failed in the middle of an important project. He did not backup in the middle of the project which was most unfortunate. To complicate matters, he did not have a startup disc included with the computer.
First step may be to extract the old hard drive and see if it is still functioning. The may require a shell which would have a SATA to USB 2 or 3 connexion. If the laptop computer recognizes the disc, you can guess that the motherboard failed. I am a Mac user so I am a little uncertain how to do this with a PC. You can then using the shell or housing with the old hard drive, as a backup or just an extra drive. You can also transfer the data from your old drive to the new laptop. I am uncertain of the procedures for a PC.
If the hard drive is dead, you need a startup disc, which may have been included with the computer. This used to be commonplace. Startup discs are commercially available, in the States, the cost was $30. Of course, you a hard drive disc , HDD, check with vendors for compatibility. There is no point in buying a solid state drive, SSD for a desktop, as its principal advantage of is saving battery capacity: not a problem with a desktop.
I am going to caution that using a startup disc may take hours, sometimes nothing seems to happen.
My brother eventually decided it was not worth the cost, about $100 and the time on his old laptop, as he now has a seven year old computer, whose usefulness may be limited.
Happy bird watching,
Arthur Pinewood :hi: