No internal hard drive detected

Hi there, I've an 8 years old Dell inspiron 1545 laptop and the operating system installed on it is Windows 7 two days ago I clicked sleep and came back after 5 minutes & out of nowhere I got a black screen with an error saying "No internal hard drive detected" and also "No boot device detected" I tried changing the settings on the F2 menu but it didn't work either I ran the diagnostics and but to no avail .. I use this computer for studying and working so I'm always using it almost 24/7 and I thought maybe this was caused by overusing? idk.

Ps: the original battery that I got with the laptop back in 2013 stopped working and I bought 2 new batteries the first one stopped charging and the laptop didn't even work & the 2nd one kept showing an error saying "not charging" every 2 days and now this happened.

Please help me I don't want to lose any data I've saved on it, all my work & papers are on this hard drive I need to get my PC fixed without losing anything.