I cannot connect to any database and there are no error messages. There are no databases listed in the tns database drop down menu in the connection window and my Oracle Home Editor show my homes as all invalid.
Check solution 7712 about Common Connection issues.
If you are still having problems connecting, check that the name of your Oracle directory in the registry under HKEY_LOCAL_MACHINE | SOFTWARE is simply ORACLE. If it has any other name other than ORACLE you may need reinstall your Oracle Client, and install with a basic directory name of ORACLE.