One of our current roommates has abandoned her property and has not paid rent or untilities for the month. She has not been home in a little over a month. Our lease is up on the 30th of this month and she is not on the lease. My roommate and I are thinking about selling her belongings to make up for the rent and utilities she has not paid. We have repeatedly texted her, asking her to come get her stuff. Our lease states that all personal belongings must be removed from the premises upon move out. Since she has abandoned her belongings do we have the right to sell them to make up for her debt?
The simple answer is no, you don't just get to sell her stuff to make up the rent. You might have to go through the courts.

But you'll need to answer this important question before we discuss it further:

With whom does she have the lease agreement?

In other words did all of you together sign one lease with the landlord or is one of you on the lease with the landlord and the other roommates have separate agreements with you?

Also, describe her "stuff."