What should I do if my gums are receding?

Recently, my teeth have been sensitive, and when I looked in the mirror, I noticed that my gums are gradually receding, revealing the roots of my teeth.

It seems that the tooth root is being irritated, causing a sensation of cold sensitivity.

When I went to the hospital, they said that in order to eliminate the sensitivity, the root part needs to be completely filled with resin treatment, but even just doing the root alone isn't cheap.

Some people say that even if you fill it with resin, it is not semi-permanent and falls out quickly.

Once a tooth gap starts, is there no way to reverse it? If treatment is possible, I plan to try treatment first, and if it doesn't work, I am considering filling it with resin.

If anyone is receiving treatment for the same concern, please share some information.