I've found following solution in CNet Forums, applied and realized that my unworking WMP 11, surprisingly started to work as it used to be. I've copied the instruction as is.
"On Vista OS ...
Go into Command Prompt as administrator from your accessories folder, (right click Command Prompt <CLICK> "Run as Administrator").
<TYPE> regsvr32.exe wmp.dll
In a moment, a window will pop up & tell you that the Registry Server command was successful, (it may take about 10-15 seconds for the prompt).
Then simply open Windows Media Player from your shortcut & you're golden.
Have fun...Good Luck...
MrJinx68"
"On Vista OS ...
Go into Command Prompt as administrator from your accessories folder, (right click Command Prompt <CLICK> "Run as Administrator").
<TYPE> regsvr32.exe wmp.dll
In a moment, a window will pop up & tell you that the Registry Server command was successful, (it may take about 10-15 seconds for the prompt).
Then simply open Windows Media Player from your shortcut & you're golden.
Have fun...Good Luck...
MrJinx68"