Tor: What should I do when Tor Browser will not connect?

Short answer

First confirm that ordinary internet access works and your device clock is correct. Restart Tor Browser, review its connection status, and check whether local security software blocks it. If the network censors Tor, try a bridge. The Tor logs and browser version are useful when asking support for help; avoid posting sensitive log details publicly without review.

Sources

Tor Project: Troubleshooting, Tor Project: Using bridges.