Project Zomboid Not Launching

Restart Steam and confirm no Project Zomboid or Java process remains in the background.
Remove optional launch flags such as -debug for one clean test.
Choose Alternate Launch and capture the first error shown; also check %UserProfile%\Zomboid\console.txt.
Verify game files and confirm the active mod set supports your Build.
If the error is graphics-related, update both integrated and discrete GPU drivers and try windowed mode.
If the error says the user folder is inaccessible, check security software and folder permissions; use a temporary alternate cache directory only when the log matches.

Distinguish nearby symptoms

A running process with music or a cursor but no image is a black-screen/display path.
A crash after reaching the menu belongs to crash troubleshooting.
An explicit Java, access, or missing-file message should drive a targeted fix.
No new console at all can indicate that the executable is blocked before normal game startup.

The Indie Stone support: Project Zomboid will not start — Official cases covering logs, drivers, inaccessible folders, and display settings.
Steam support: game not launching — Support troubleshooting discussion.
Community launch failure report — Community example; verify the signature first.