c# - .cs files can't be opened anymore in VS 2013 Professional Update 4 -

i'm facing problem can't open .cs files in visual studio 2013 after 1 day.

it started on monday: opened existing solution , tried open program.cs file instead met following error message (rough translation):

no exports found meet constraint:

contractname

microsoft.visualstudio.utilities.icontenttyperegistryservice

requiredtypeidentity

microsoft.visualstudio.utilities.icontenttyperegistryservice

i tried opening .cs files in different solutions , got same message. exception being: visual studio instance opened before visual studio instance in exception first occured was/is not affected this.

i managed working choosing repair visual studio installation , rebooting worked until next day.

i tried searching message got nothing far.

delete or rename folder:

c:\users\\appdata\local\microsoft\visualstudio\12.0\componentmodelcache\