Might be corrupt settings; backup/delete the SQL Developer/systemXXX directory in the hidden Application Data under your Windows profile to reset your installation to defaults.
Else, if you run from \sqldeveloper\bin\sqldeveloper.exe, what output do you get in the opened console when starting up and querying? This could help diagnosing the problem.
I did that only for that dir there were other files there beside that dir CodeTemplate.xml MigrationErrorLog.xml SqlHistory.xml and MigrationErrorLog.xml.lck and a folder called tmp should I have removed those as well? I still get the same error.