The el.db file is a SQLite database file. You can open it with an SQLite database viewer or manager.

The simplest cross-platform solution I know of is the SQLite manager add-on for Firefox. It is quite comprehensive, considering that it is a browser add-on. You can download it from here if you have Firefox already installed:

https://addons.mozilla.org/en-US/firefox/addon/5817/

If this does not suit you, just search the web for "sqlite browser OR manager" and see if you find something useful for your system.

The SMSes are stored in the table "Events". You can search for a string in the SMSes using the search button in the "Browse & Search" view in SQLite Manager. Search in the full_text field and select "contains" from the drop-down menu.

Good luck finding your SMS!