I’m not sure I can recall a situation where a country has decided to move from a widely-traded hard currency as a medium of exchange back to its own original currency - especially one that could be practically worthless in a relatively short period of time.
An albeit extreme analogy would be Zimbabwe which is for all intents and purposes now a US Dollar economy as people have simply lost all faith in the local currency. The Zimbabwean Dollar is still in circulation, but is effectively toilet paper.
Now try to imagine what would happen if the situation was reversed - the Zimbabwean Central Bank announcing tomorrow that it was forcibly converting US Dollars into Zimbabwean Dollars and then using the latter as the sole national currency.
Everyone who had US Dollars, or could get hold of them, would continue to use them no matter what the Government says or does. Those who didn’t have any US Dollars (invariably the poorest sections of society) would then be forced into absolute penury.