Lightroom 4 doesn't see raw photos anymore

[default9miov564bqu8]

I don't know why but suddenly my lightroom 4 doesn't see my raw photos. It sees only jpeg one. Why? What can I do? Is ther an update, a new version? It's been only 2 months since I used lightroom and then I could see my raw photos. I do not understand what happened?

[Rob_Cullen]

Please include the following in your question:
Adobe product and Version number A Screenshot of the info panel from MENU: Help/System Info...
Operating system and Version number

Your exact Camera Brand and Model number.
The full text of any Error Message(s)
What has changed since you could see your photos. (a new camera?)
Screenshots of the problem.