lock button mix walkman

[mix11]

Hi,i have the mix walkman and its lock button broke down. It isn't anymore on the phone and when i try to lock or switch off, the phone ,it doesn't work. So the phone switches on automatically when i put the battery. What can i do ? Is there any way to lock phone with another button or anything else ? Please help me. Thank you in advance

[Uliwooly]

You need to fix the phone, either take it to a Sony repair center or DIY, you can buy the part online/ebay