About a month ago, I had the same problem, but no one really helped me. Ever since 1.7.10, I played forge till I practically quit Minecraft entirely getting bored of the game. I'm back on Minecraft of course and hoping to have a smaller addiction to mods than I had before.
But I can't exactly install Forge. On another account I did, but I believe it just fixed the universal libraries and files and not the singular stand-alone account libraries. So-- I DON'T KNOW WHAT ELSE TO TRY.
I tried affixing the forge folder from the other account to this one but it kept crashing halfway on the launcher loading screen.
I tried Manually finding the separate lost Libraries but it was no use, I don't think all of them are downloadable.
I tried older versions of 1.14 but it leads to the exact same problem.
The only luck I ever had was the shortening of the libraries from the other account and successfully installing from an older forge launcher on minecraft 1.12, and it installed like it was nothing.
Is there anyone that has the brain to assist me and tell me how I can fix this problem. Please. and Please reply back to me.