Interface Preferences

The Lightroom interace is and has been dark charcoal with light grey text since it was first released in 2007. Any changes since then have been very minimal, and didn't impact on the colour/contrast of the UI.

It would be helpful if you could submit a screenshot of the application as displayed on your monitor.

Lightroom Classic's "background" setting refers only to the blank space surrounding a previewed image. This is done to assist perceptual judgement of the image, not for interface legibility.

The first check to make, is that your graphics driver is up to date and that there is not some issue with graphics acceleration. If you mean "totally unreadable" literally, there are known problems of this sort.

There is no menu option provided to alter the appearance of Lightroom Classic's tool panels, menus, dialogs etc. The interface uses many shades of grey for different degrees of contrast against the fixed dark background. So changing that background on its own would not result in a high-legibility interface; all the interface elements' shades of grey would also need to change strategically to achieve an equivalent amount of contrast against each other and against the new chosen background colour. Also this change would affect how images are perceptually seen.

If by "totally unreadable" you mean visible, just not very easily - and there is not a display system / graphics driver problem - this may be just an issue of getting used to it. But also, it may be that how your display is adjusted, or your working environment and lighting, are responsible. It is not necessary to crank up display brightness to the maximum: many people do successfully and comfortably use the dark-background LR interface even with e.g. a display that's profiled to a lowish luminance target (for print matching purposes). So I would advise seeing what can be improved about your display contrastiness (this may even be set too high), and/or about the context in which you are viewing that display.

However if your own vision cannot discriminate between shades of grey very well, Lightroom Classic's lack of high-legibility interface options may rule it out for you. Many graphics applications are AFAICT designed on the pragmatic / economical basis, that prospective users will have self-selected on more-or-less "normal" vision.

Are you referring to Lightroom Classic, currently v9.2.1

or

Lightroom, currently v3.2.1

Fairly sure you mean Lightroom

This is the Lightroom Classic page

Link for Lightroom page is: 

https://community.adobe.com/t5/lightroom/bd-p/lightroom?page=1&sort=latest_replies&filter=unresolved