what is the cheapest ticket that i can get

That question is impossible to answer without more information. 

Where do you want to travel? How many days do you plan to travel?

You options are the Swiss Travel Pass or normal tickets from the Swiss Railway. There are daysaver passes that can be rather cheap if bought well in advance.

Do you want to travel by the swiss yellow post busses that cover the parts of the country where you can't get by train.

Do you want to use public transport? Will you in that case stay in an accommodation that provides a card for free public transportation?

Are you planning to visit many museums?

The Swiss Travel Pass includes, apart from train rides, also free public transportation, free travel with the post busses, free entry to many museums and discounts on others.

I suggest that you look at what's included in the Swiss Travel pass and compare that with the cost for other options. 

Thank you very much

we are planning to stay for 5 days, in July. trying to see villages around geneva and come back in the evening to geneva. we are open for bus or train.?

swiss travel pass , how much it cost for family?

is there a special priced ticket that work for family?

yellow post bus how much it cost? for family

Prices are available online. Children under 16 y.o. travel for very cheap or free with a Swiss Travel Pass. However that does not apply to 16 y.o. children and older, they pay full-fare.

For 5 days : either a Swiss Travel Pass or 5 Saver Day Passes : valid all day on all Swiss trains, buses, boats, trams (except mountain railways). Prices start at 52 CHF 2 months in advance. If regular tickets cost less than 52 CHF per person, of course do not buy a Saver Day Pass. But Swiss tickets are expensive (as an example : 45.60 CHF full-fare for Geneva - Lausanne return) so Saver Day Passes are good value.

For youth under 25 y.o : there's a new offer called Friends Day Pass. The card costs 80 CHF and up to 4 people under 25 y.o. can travel with it. 

So for each day you'll need 3 x 52 CHF Saver Day Passes (wife, 26 y.o. child and yourself) + 1 x 80 CHF Friends Day Pass.

Please note that both the Saver Day Pass and the Friends Day Pass (but also the Swiss Travel Pass) do not work on mountain railways (such as Jungfraujoch, Gornergrat, Schilthorn). There are a few exceptions (map available online) :

- Rochers-de-Naye

- Rigi

- Stanserhorn