I found out through another employee, I've received no notice! What do I do now? Maybe someone else has bought it? Maybe went bust ? Does this mean I am redundant? What do I do now?

Have you confirmed this with someone representing the company itself? Have you tried to contact management or HR?

Once you get official confirmation, then you apply for Unemployment and start looking for another job. (Assuming you are from the U.S.).

Where are you at. What type of company? Is it a large company or a small family owned business. Often in small family owned business a person has a accident or sick and they close till arrangements are made.

But if in the US, and they are "closed" you are out of work and need to go file for unemployment.

What type of work do you do for them that you were not aware? I gather you don't go into a site on a daily basis.