This is actually a very good question.
The short answer is:
Freelancer accounts may be suspended for a variety of reasons.
A freelancer might have been discovered to be a complete fraud or a terrible criminal. In which case you probably wouldn't want to work with her.
Alternatively, freelancer accounts can be suspended for completely benign reasons, including being randomly selected to undergo identity verification or needing to undergo brief, routine checks associated with financial errors connected to clients they are working with.
You (as a client) don't really have any control over a freelancer's suspension status, and Upwork representatives won't tell you anything about it. But you are welcome to communicate with a freelancer and ask her if she thinks the suspension will be resolved soon. If so, maybe you can wait for her to be available.
Otherwise, to keep your project on track you may need to work with other people and ask the currently-suspended freelancer to send you a note to let you know when she can work for you again.
Accounts are suspended for many different reasons. Take a look at this help article for details on what is considered inappropriate behavior. Unfortunately, we won't be able to share information about this particular freelancer's account status here in the Community. You can consider hiring a different freelancer to complete the project for you.