Corrupt startup disk quandary

[Laodah]

Running Sierra 10.12.6, MacBook Pro Retina 13-inch.

Ran Disk Utilities after a freeze, said I needed to repair start-up disk. Ran DU several more times, no love.

Restarted in Recovery mode, ran DU several times, said everything was fine, but upon restart to normal, DU still says it needs repairing.

In Recovery, the startup disk remains grey, so I can't run Repair on it. Tried to mount it, was prompted for password, but it won't let me type it (or anything) in the blank; I hit the keys, nothing happens. As this is the disk DU doesn't like, and I can't repair it while grey, I suspect the problem is that.

Any suggestions? System is crashing a lot; I have a feeling it's about to dump me entirely if I can't get it repaired.

Thanks.

 

[FarmerBob]

I have had that happen. What I did was start up on an installer USB with the current version of the OS that I was running and reinstalling it over the current install. It "refreshed" it beautifully without any damage to my files or set up. Every so often I run it to keep things fresh.