Here's a correct version of your sentence:
Retrospective feelings make people imagine a future which is better than the present.
I'm not sure if this covers the meaning of what you want to say exactly, if it doesn't, maybe you could explain your idea a bit more?
In any case, feelings should be pluralised in situations like this when we're talking about unspecific emotions felt by many people. As a result, the verb needs to be the base form without the 's', because we're dealing with a plural subject.