Please excuse the reply in English. The solution is simple, but a lot of work. Take each coin and identify it. The Numista page will often give a value for the coin.
I inherited a coin collection from my grandfather a few year ago, mostly German coins actually, and went through this process. I don't intend to sell them, but I thought it was fun. Here are some general rules I found. (These are from my experience with mostly German coins from about 1400 to the 1920s. I'd be interested if other collectors agree or not)
1) The current value of a coin depend a lot on the value of the coin when it was made. Big silver coins, and gold coins were valuable, and are more valuable now. Copper, bronze, and small silver coins are less valuable.
2) If the coin is from after 1900, it is probably not valuable, except for the melt value of the metal.
3) The value of an older, less common coin is strongly affected by the condition of the coin, a coin with very little wear will be worth much more than a typical coin of that age.
I have tried to restore a few coins where they were so covered with rust that I couldn't' identify them, but the general rule is: Do not clean the coins!