Q: MacBook4,1 early 2008 - hard disk crash

My oldest son bought an new MacBook Pro with the excuse that the hard disk of his old one (MacBook 4,1 early 2008) had crashed.

Now I would like to replace this hard disk by a SDD and at the same time add some RAM.

For the moment there is one item that keeps me busy, the fact that I don't have any disks to install the original OS.

Are there any suggestions?