Unable to open window media player and sidebar in window Vista

Follow these steps :-

1. Open command prompt by going to Start/all programs/accessories/ and right clicking on the icon - select 'run as administrator.

2. When the command window opens type:
regsvr32 scrrun.dll
and press the enter key

3. Now type
regsvr32 jscript.dll
and press the enter key

4. Now type
regsvr32 msxml3.dll
and press the enter key.

5. Now type
regsvr32 atl.dll
and press the enter key.

6. Restart your computer and check