OK. There were no previous restore points. What I would like to do, I think, is roll back to the last major release... What happened here, I think, is that the person did not update until just this week, along with the Tuesday release. The wifi immediately quit working and I can't find a new driver anywhere. So I need to roll back the operating system to pre 1804 and then turn off all major updates for like 6 months, until Dell catches up. However, the rollback menu provided by the update does not include rolling back the major release... it only lists the security updates.
(By the way, from the forums, Dell is not very responsive to changes like going to 1804, which is sad and should be considered by anyone who is thinking of purchasing a Dell computer! Dell makes drivers proprietary and then doesn't keep pace with changes.) So, I'm thinking I will have to reload the operating system from scratch. (I've had lots of update problems with computers, and most seem to occur on computers that were updated from Windows 7 to Windows 10 during that grace time. There is something left on the computers that "does not compute" as future operating system versions are released.)