How to open a message database(.db) file from Sony Xperia phone in computer? So I had backed up my files and messages from sony xperia phone and saved all files in the computer....

Now I need to open the messages file in the backup folder which has the format of .bk...

I tried to use 7 zip to extract the .db file...

But when I opened the .db file in Notepad it appeared haphazardly with many characters and the messages were there but were jumbled in between the characters...

So I want to view them in a proper format..... Any suggestion or advice?
.db files are not plain-text files, so Notepad is the wrong approach. Those are SQLite databases, so you will have to use some SQLite browser for the task. The linked Wiki page gives you some more details. SQLiteman would be a good choice, and there's even a portable version available. For an alternative, there's also SQLite Browser.