Try this procedure
1. delete ClientRegistry.blob from steam folder. It is auto rebuilt. Check steam list to see if they show?
2. Turn off the firewall and antivirus. Check steam list to see if they show?
3. if these dont work try to defrag you HD and from steam from games view. Check steam list to see if they show?
4. check for file consistency also from from games view. Check steam list to see if they show?
5. log-off steam and log back in from steam menu make sure it prompts you for a password. Check steam list to see if they show?
6. as a last resort at leats once a year delete the czero directory and re-BANNED TOPIC from steam (back up your config.cfg, userconfig.cfg first)
got it of the mind forums lolz