I need to do Astrids Dark Brotherhood quest, in Markarth, and yet my bounty is 5000 from a previous quest, I now have the money but the guards won't let me pay off my bounty, anyone able to help out?

I need help, I can't get to the girl to go further.

If you can't pay the bounty. Then I suggest that you go to jail and serve your time.
Other than that, you'd have to get the gold required to pay off your fines.

or sleep at a safe place for a few months.

What do the guards say when they confront you?

I can't go to jail, It will not let me and also I have Beast blood.

@NordhNet
They give me the guild choice then say I can't do that then i say I submit then they don't let me

I still need help when ever I enter the reach they attack.

Do you have any companions? If you have a companion with you, as soon as the guards attack, your follower attacks them, and even though you may submit, they won't.

The other issue may be your faction alignment. Are you obviously aligned with the opposite faction to that which runs Markath? For example, if you are a stormcloak, or closely aligned to them, guards from Empire cities and towns can attack you.