To say ´I can´t´ in turkish you use the suffix ´emez/amaz´

example

You can´t be

ol + amaz + sın

olamazsın

Looking at the chart above have you noticed anything different?

Try looking at 

I can´t

and

We can´t

Can you see anything different now?

With you can´t, he can´t, you can´t and they can´t you use ´emez/amaz´

but

with I can´t you use ´emem´

and

with We can´t you use ´emeyiz´

So for the sentence

I can´t come 

gel + eme + m

gelemem

We can´t stay

kal + ama + yız

kalamayız

Look at some examples below

Now try making your own sentences and seeing how well you do