We've had a CiviCRM site running for a while. Just recently our payment area is missing on all our events, contribution pages, and membership pages. As such, people cannot select to do Paypal, credit card (Authorize.net), or pay later.
Here's an event: https://www.zendust.org/civicrm/event/register?id=158&reset=1
Here's the donate page: https://www.zendust.org/civicrm/contribute/transact?reset=1&id=3
I completely cleared out any custom template pages we had in our CiviCRM files directory. This is a fresh install of Civi - I had to do the whole database dump and then into a new database and then run the updates, as updates were failing. I don't know if this has been an issue ever since we redid the database or not, as folks just noticed it.