In English, a verb phrase includes an optional auxiliary verb (or "helping verb") such as "have", "will", "shall", "do" or "be". The auxiliary verb appears in front of the main verb.

When the auxiliary verb is present, the auxiliary verb takes on the inflections of tense (past, present) as well as person (I, you, they, ...).

The main verb remains in an infinitive or participle form.

For instance, suppose the auxiliary is "have" and the main verb is "be". In this case, "be" turns into the participle "been", and then "have" undergoes various inflections:

I have been there.

I had been there.

She has been there.

The "been" does not change. Now if you don't have an auxiliary verb, then the main verb takes the inflections:

I am there.

I was there.

She is there.

It is exactly the same thing when the auxiliary is "do", and the main verb is "like". The auxiliary "do" takes the inflections. Here, "like" is in a nonpast/infinitive form rather than a past participle:

I do like ..

She does like ..

She did like ...

If we take out "do", then "like" has to take on the inflections for person and tense:

I like

She likes

She liked

It is the same for all other auxiliaries. For instance "shall" with "go":

I shall go

I should go

and "will" with "go":

I will go

I would go

or "be" with "go":

I am gone

She is gone

She was gone

The trick is knowing which form of the main verb to use: participle or plain present. "I am go" and "I will gone" are ungrammatical!