Will it cause banks not to have enough bitcoin in their reserves?
Why would you still need banks if bitcoin would become a world currency?
Will it affect a price adjustment on goods and how will it affect the economy as a whole?
This will be adjusted based on the simple principle of demand and offer, the less bitcoin there are the more they are valued.
But it depends a lot on the percentage of bitcoins lost compared to the ones in circulation in a time frame, and it depends on how you define lost. If let's say a government would f their wallets and 100k bitcoin out of 10 millions would be lost in a matter of hours, that could start some fireworks....
Will there be a deflation in prices and will the value of Bitcoin be stable at some point and then become volatile because of this?
Choose one or the other.
The price of Bitcoin will always be volatile the only thing we don't know is by how much. And more important...relative to what?
Will it affect a price adjustment on goods and how will it affect the economy as a whole?
As for the economy as a whole...I have no clue and this is a question far to complex to be answered since we don't have a single example of even a small community running on bitcoin.
Referring to the goods, it will be the same law of offer and demand.
Less bitcoins, more cheese you can buy, but at the same time, if less cheese on sale, less cheese you can buy even if bitcoins keep getting lost.