My 98 honda civic heat gauge was showing high temperature, I took it to mechanic and he replaced 2 heating hoses sine there was a leakage of coolent. But after that temperature gauge is not functioning at all, he replaced temperature switch/fuse etc. but still gauge did not move. Now he do not know what to do about it. Any suggestions.

This link from the Sticky may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-11.html#post2043857