Copy A Mkv File To Mp4

Excuse me for rambling on for just a few minutes, please bear with me.
Typing this has been a nightmare. Half of my keyboard keys have faded so much l have to keep altering everything.
Anyway, a new QWERTY keyboard is on its way from the UK, yipee!
Right then, this is my problem.......
Have received a film in mkv format and it plays fine on the pc.
When l copy it to a usb stick and plug it in to my super duper LG player to watch on the tv - Error format.
Ok, have tried both Freemake and AVC to convert this one off mkv file to MP4.
My system got totally trashed and it took me a day to put everything right.
If l go to look at any of these so called "freebie" sites, they all appear to be commercial trials.
Watermarks and the like removed for a cost.
I am so out of touch with everything now, and all l want is a one of program to convert my mkv file to mp4.
Has anyone out there got any ideas?

 

Try VLC Media Player.
http://www.majorgeeks.com/files/details/vlc_media_player.html

Here are the instructions.
http://asawicki.info/news_1615_how_to_quickly_convert_mkv_to_mp4_file_using_vlc.html

 

Sorry peeps, how rude of me not to reply asap, but have been a tad busy of late.
You have been the only site that has responded to my original question in the shortest time.
ELDON
After all this time, didn't realise that VLC can actually convert file formats.
Never had to use it up until now, but for this one off file.
Download VLC and instructions you gave. Followed through and got a bit lost.
Click on the icon button that has hint: "Edit selected profile".
On "Encapsulation" tab, leave "MP4/MOV" selected.
On "Video codec" tab, check both "Video" and "Keep original video track".
On "Audio codec" tab, similarly select both "Audio" and "Keep original audio track".
There was no icon button that has hint whatsover!
I have joined the VLC forums and will pose that question to them.
Thanks anyway.
PLODR
Pazera Software? Never even heard of them but thought l'd give it try. In for a penny etc...
Blimmin' heck, absolutely brilliant! Ok, took me just over the hour to convert it to mp4, but my other half is now watching it as we speak.
It is only used for converting mkv to mp4, but that suits me fine.
Thanks so much for that, really appreciated.
Best Regards
WTC