After the upgrade to last software version no longer play some files in mkv format. Return to the previous version does not work even with the help of Russian support for 4 months.
On the screen there is no button to return to the previous version and the device does not understand/does not read a USB device with the old version.
Russian support refuses to change the device, and advises to change it in the shop where I more than a year ago bought your device 
How do I still solve the problem???
There are hundreds (if not more) posts in this forum about how to do a firmware rollback.
Thank you.
Excuse me, but in my case device does not see files on USB and on TV screen connected with my device is not button for Rollback.
Couldn’t you give the link any such post…
What Firmware are you currently running ?
To find out … go to Setup > About
Post the number here and i’ll provide a step-by-step guide for you 
Thank you.
version 1.03.07
ok … the only version available to firmware rollback to is 1.00.42 (which WD provide here )
so if you’re happy to do that … then follow this guide EXACTLY step-by-step
[1] small flashdrive (2,4,8 GB) formatted FAT32 … completely empty
[2] download rollback firmware: http://download.wdc.com/wdtv/wdtv_rollback_1.00.42.zip
[3] extract all 4 files onto the root of the flashdrive ie. No Folders
so you should only have these on the flashdrive
wdtvmediaplayer.bi2
wdtvmediaplayer.bin
wdtvmediaplayer.fff
wdtvmediaplayer.ver
[4] Before inserting the flashdrive … check the detect New Firmware setting is “On”
Setup > System > Auto Detect New Firmware > On
[5] Power off the WDTV (Press and hold Standby button for 5 seconds … switch off at the mains power)
[6] “Safely Remove” the flashdrive from your PC and insert it into the front or rear usb input on the WDTV
[7] Power On the WDTV
[8] New Firmware should now be detected “New Firmware” notification will appear in the Home Menu (or if using Grid Theme, it will be an Orange Alert ! at the top right of screen) Press OK
(it will say 3.00.42 don’t worry, ignore it) … press OK to proceed)
[9] wait until finished (it can take several minutes … it should not take longer than 10-15 min)
[10] It’s also recommended after a Firmware Rollback (or upgrade) to do a Factory Reset
Setup > System > Device Reset > Reset All Settings Back to Factory Default
[11] when finished (optional) disable the New Firmware notification
Setup > System > Auto Detect New Firmware > Off
