Refresh rate issue: do Dell monitors support 24-25 Hz?

I plugged a 2018 Mac Mini to a 21.5 FullHd Dell monitor and it was running fine at 60Hz until i switched Mac settings to 24-25Hz , and screen blacked out. I can’t change settings back because I’m blind and all reboot and reset procedures didn’t work. So I’m wondering if I can plug a new monitor to fix the problem, but it has to support 24-25 Hz I suppose. So which Dell monitors does so? Thank you!