During xmess and summer, one needs to work elsewhere about 2-3 months. Flowers should not die during that time. What kind of flowers should one have and how should one keep them not to die? A lot of watering before leaving? Keeping in cold/dark place? Which flowers?
As you've explained you actually mean houseplants, flowering or otherwise, then your best bet would be cacti (as suggested already by someone else) and succulents generally, such as Aeonium, Agave, Aloe. As far as succulents are concerned, they can cope for 1-2 months during winter without water, but must be watered normally from Spring through to Autumn, so if you're absent during winter, they should be fine, but not otherwise. Note that succulents do require air movement, even in winter, so will not particularly appreciate a completely closed up environment.
Houseplants that need no maintenance at all for many months are rare. Why not either give them to someone else to look after, or let them die and replace them when you return? Especially since these are theoretical houseplants that you don't own yet, since you ask which kinds of flowers would be best.