How to change partition letters using DOS?

[Buzzanytime]

After uninstalling AVAST, My computer could not restart. Partition letters have been altered during process and need to be set back to correct values. The System reserved volume has now become C. This should have no letter and is normally hidden. The C partition is now marked as D. This is where the Windows installations is stored but it cannot open while the letter is wrong. There is also a data partition, formally D, now marked E. The DOS prompt is only method of working on the computer, Windows cannot open.

 

[LMiller7]

Welcome to the forum.

Where are you seeing these changed drive letters?

Edit: Drive letters are defined within the Windows registry. If you are using some utility outside Windows it will use drive letters that have been arbitrarily assigned and will have no relationship to those used by Windows.

I don't think drive letters are your problem.

 

[Buzzanytime]

I used the DOS DISKPART command, see attachment. If you call the same command on a healthy computer, the hidden partitions have no letters and Windows is in C. Certainly the letters have changed because using DIR also confirms Windows is now in D.

After taking screen cap I changed letters back but as you warned that does not fix it. Diskpart shows one other thing wrong.
Boot Disk : No.
So do you know how to change this to a boot disk?