I purchased a refurbished Iphone8, which seems to work except it doesn' t ring when i get a call. I've tried all the fix solutions, with NO luck. it does have a check mark on silent, when in locked screen. I can not get it to go off. my Ipad rings fi

If "I noticed the silent mode is checked next to on locked screen." you mean the Silence While iPhone is Locked setting in Do Not Disturb, be aware that setting is only applicable if Do Not Disturb is on.

Since you didn't list all of the things you tried, the following may or may not help:

Some things to check:

The ring/silent switch on the left side of the phone. See: https://support.apple.com/en-us/HT208353

Settings > Phone > Silence Unknown Callers: https://support.apple.com/en-us/HT207099

Do Not Disturb: https://support.apple.com/en-us/HT204321

If none of the above, also try restarting: https://support.apple.com/en-us/HT201559

Did you check the mute switch on the side of the phone above the volume buttons?