Every year, almost, since 1965, Italy has issued high-denomination coins for collectors in silver. There are dozens of different patterns, but the silver content, and therefore the value, stays the same. This page gives a listing of silver content. Once you find your coin and its silver content, go to kitco.com to get the current silver price. Multiply this price by the silver content and you get the nominal value of the coin.
For instance, suppose you have a 1965 500 lire with 0.295 troy ounces of silver, and suppose the current price of silver is $30 US dollars per troy ounce (look it up, it changes every day). The nominal value of the coin is then 0.295 x 30 = $9 US dollars. A particular coin may sell for a few dollars more than this, especially if it is in superb condition.
The listings below include only solid silver coins. Some denominations were also minted with bi-metallic designs, with inner and outer rings. These bi-metallic coins are made of non-precious metal and are worth face value.
For the silver coins ...
500 LIRE (L500)
1965 to 1991: 0.295 troy ounces silver
1992 and after: 0.403 ounce silver
1000 LIRE (L1000)
1970 and after: 0.392 ounces
2000 LIRE (L2000)
1998 and after: 0.430 ounces
5000 LIRE (L5000)
1993 and after: 0.483 ounces
10000 LIRE (L10000)
1994 and after: 0.591 ounces