On the asset entry worksheet its asking me to enter the Recovery Period for an asset my self-employed company sold. What goes in this block and is it in months or years?

Years. As for the number of years, it depends on what the asset classification is, and on what date it was placed in service.

If you sold the asset, then you "should" have been depreciating it already, from the date it was placed in service. In most cases (not all) assets that have a class life of less than one year are not depreciated, and are most commonly not treated as assets at all.

It is a really bad idea to be directly filling out the forms and worksheets unless you really know what you are doing (and your question indicates that you do not).  It is best for you to use the Step-by-Step interview.