It is worth only about 50 cents. You can find the detailed answer here http://wiki.answers.com/Q/What_is_the_value_of_BancaD'Italia_1000_lire_mille_made_in_1943_without_2_children_on_the_back_of_the_bill_worth
Nothing since the lire doesn't exist any longer. If you can exchange it for Euros it could fetch a few cents, but I don't think much. I was in Italy in that time and the lire was really low in value. I got a good exchange rate for my dollar to lire in that time.
At the present time, the currency exchange rate is one Turkish Lira is worth 0.47 US Dollars. This would mean that 5000 Lire would be worth 2353.22 US Dollars. It is important to note that the exchange rate changes daily.