I am planning a 5 week trip round Europe and part of that plan is to go from Vienna- Venice- Naples - Rome- Genoa- Nice- Milan. looking at a Interrail map, this looks possible but when i search for the train times there comes up with no options.
All of these trips are possible. On all of these routes there are many options to go. For all of these trips there are timetables available.
As your posting lacks the most relevant informations needed for a reliable answer (e.g. where are you searching for timetables for which date - you should include these important informations, please),
I assume: You are trying to get timetables for a date in the future where there are simply no tlmetables uploaded yet (for Italy, most are missing from June 11th). If this is the case, just do a research for tomorrow and you'll get an idea what the tlmetables will look like.
If you did use it: I recommend not to use the Interrail / Eurail planer. Try https://fahrplan.oebb.at/ instead - that's the best company to get mandatory reservations for your trips, too.
Although a slightly larger booking fee you can get reservations at Italiarail.
For Nice you need to transfer at Ventimiglia onto a regional SNCF service (every half hour no reservation service).
When returning to Milan there is a 2 hourly Intercity service direct (small mandatory reservation fee) from Ventimiglia. Do not take any of the services with changes in Turin,
Venice - Naples and Naples to Rome are served by a high speed line that goes on to Salerno - about 30 mins past Naples - much nicer and has a frequent local service to Naples and Pompeii.
Also consider Florence and Bologna - they are on the same high speed line.