Default Restore SMS backup-ed to sd card

Hi guys I need some big help. Well I have backuped my sms to a sd card. Now I have there one very important SMS but cannot read it. Neither I can read it on my PC nor on my phone using some backup tools. The file doesnīt have any extension it just says file. Does anyone know how to help me?

The fileīs size is 284 KB, so there are messages in it,but I just donīt know how to open it. I tried a lot of sms restore and backup programs from the goople play store.