1. Yes. “ the U.S. Embassy Accra in Ghana is temporarily suspending routine immigrant and nonimmigrant visa appointments, effective March 17, 2020. We will resume routine visa services as soon as possible, but are unable to provide a date at this time.”
https://gh.usembassy.gov/u-s-embass...d-contain-the-spread-of-coronavirus-covid-19/
2. ?
3. It’s not true that “no-one is allowed to enter”. There is a ban on people entering from certain countries, mostly in Europe. At present most of the world is not those countries. If you cannot use an issued immigrant visa due to circumstances beyond your control you can get it reissued (note: you normally have to pay the visa fee again). For now just keep watching and waiting.