This is not my computer, but a friend's.
This laptop had an update but when it would do the update it would turn to a black screen with the turny icon, and stayed this way for a good 17 hours. She held the power button and turned it back on again and when she was able to get back in to her computer no files responded to her, so she put everything on a flash drive and factory reset it. Today when she went to reinstall everything it took forever to log in, and when it finally did everything was slow. Any ideas?

How long did the factory reset take?

Doing a factory reset was excessive without first uninstalling and re-attempting the update and also verifying the system's storage device (hard drive?) with the device manufacturer's diagnostic software available on their website. If a system is sluggish and unresponsive to input and there is no software causing high CPU utilization, often there is a hardware issue somewhere. With a laptop, the easily replaceable and tested components are drives and memory. CPU fan failure or blocked airflow can also hobble performance. Reinstalling software via a factory reset will not remedy faulty or failing hardware.