i found such sentence in internet:

Bir daha o kadının yanına gidersen geri döndüğünde aileni bulamazsın.

i understood everything except last word.

So why it´s not bulamayacaksın instead of bulamazsın in that case?

Bulamazsın ( you can´t find )

Bulamayacaksın ( you won´t be able to find )

Because tenses are very flexible in Turkish. For example sometimes you can use aorist tense to talk about future and even about past. In that sentence using aorist tense he/she talks about future.

Here is an example. 

1)If you are talking about a past event this sentence can be translated like this:

Onu gördükten sonra yanına gider ve selam der.

After he had seen her, he went near her and said hi.

2)If you are talking about a future event this sentence can be translated like this:

Onu gördükten sonra yanına gider ve selam der.

After he sees her, he will go near her and will say hi.

Thank you Gokuyum. 

One has wanted to tell about a certain situation. If one used the future tense, one would just indicate a result. One would inform him. But he was advised by using simple present.

Both are correct as well-nigh the same as each other in that case. Like gokuyum has stated, the tenses (especially present simple and present continuous) are flexible in Turkish.