All prices are already being adjusted all the time - what is the problem?
Greece and Spain right now do not have their own currency. Their monetary policy is dictated by greater powers - like Germany. The Euro is a 'strong currency' - it's the only way a currency union can work. There are very strict rules for how money is created.
When an economy crashes or sinks, sometimes governments want to print some easy money to 'stimulate' the economy, and a weaker currency will help exports.
Also - one 'price' that will not change easily is wages. Powerful, government sector unions will never accept a pay cut. Neither will private citizens really.
But in reality - 'the nations workers' simply are not as productive - and 'everyone needs to take a pay cut'. Not gonna happen.
Instead of 'pay cuts' companies and govs just 'hire less' hurting the economy even more.
Welcome 'monetary policy'. It's a tricky game, but they can inflate away debt, and push wages down a little bit, vis-a-vis other nations - to reflect the new condition of the economy.
Also - war, and existential shock. Monetary policy tools are important then for nations to survive sometimes.
It's a risky thing, and prone to mismanagement and certainly when politicians get their grubby hands on the Central Bank - it usually runs amok. This is the 'historical' reason a lot of people like 'Gold standards' and 'hard money' - because some tin-pot dictator can't dilute their cash.
But intelligently managed currency has elasticity - which helps smooth over bumps.
Is the short answer.