To do so, you simple can run a program called regsvr32 in the run prompt in the start menu. Tell it to run: regsvr32 C:\Program Files\Windows Media Player\wmpband.dll
If that doesn't work , simply copy the file (wmpband.dll) from the media player folder, and paste a copy directly in the C: folder. Then do the run command again: regsvr32 C:\wmpband.dll
The second option worked for me (it will tell you if it was successful or if it failed). Then, restart Windows Media Player, right click the taskbar, go to toolbar, and the Windows Media Player should be back.