How to revert styles in Ubuntu?

Question

linux

For some reason the styles disappeared in some parts of the system.
For example, what nautilus looks like now

Answer 1

Try to create a new user and check how it manifests itself. If so, then this is a system-wide problem and then you will need to pre/reinstall the necessary packages.
If the problem does not appear, then the error is either related to access rights within the home directory, or the presence / absence of files or configuration. Then it's easier to delete user settings by recreating them when you log in again.