Drive letters changed and now I have to change thousands of links to point to drive L instead of I.

The other folks responding in your thread are correct, but I'm going to guess that you don't have the power to remap your own drive letters, because it's something your IT department forced on you, and they're not going to make this really simple change for you. (I did a true legitimate double-take when I saw your post, because that is exactly what my own IT dep't. did to me in 2004 or thereabouts... even the drive letters in question were I and L.)

If I'm correct in my above suppositions, then this script by Kasyan will serve you well as a de-panic-ifier and general tonic. It is, overtly, a file-relinker for people who have lost links in a server migration. I used this other Kasyan script, which might work just fine for you, as all it does is change the drive letter. 

Because these scripts are ancient (written for CS3), you might need to make a folder in your Scripts folder called "Version 6.0" and run those scripts from inside that folder. 

I would remap drive L to drive I instead.

On Windows, this happens from time to time, when you plug in external drives. They take the next free slot on the first connection. Thereafter, the drive letter is sticky, except if you connect a different drive and that drive takes the slot. As you were on I and you are now on L, I suppose, I, J, and K are taken. To avoid this, I voluntarily used higher letters for critical drives (x, y, z), so that they don't get dislocated. In your case, it's too late for that. Please find here how to change the drive letters on Windows 10:

• Disconnect the culprit drive, or change that one's drive letter before this (same procedure as described).
• Reboot (VERY IMPORTANT).
• Check that the "I" drive letter is free.
• If your L: drive is not yet connected, connect it.
• Search for "Disk management" on the start menu
  
• Right Mouse Click on the drive, whose letter you want to change (here E:)
  
• Chose "Change Drive Letter and Paths…"
• Click change:
  
• Chose one of the free letters (I in your case):
  
• Disregard the upcoming warning and click "Yes".
  
• It's done, you may want to reboot to see if the drive letter now sticks.

NB: If you looked well, you saw that my backup drive uses Z:. A second one uses Y: (currently unconnected). They will never conflict with other drives on my system.

Please tell me if this worked. In Windows 11 or Windows 7, you should proceed similarly.

Can't you remap your I drive as L drive? Just create new drive L linked to root directory of I drive.