I have a compaq presario cq50 notebook. everytime i try to start my laptop bootmanger is missing, what can i do to fix it

Use the Restoration Disk (CD), and perform a Repair. (Non-Destructive Installation)
A Repair just repairs the basic Windows files needed.
{Boot Manager is one of them}

[A Destructive Installation is just that.
It restores the computer back to Day 1, just like it came from the factory.

All personal data is wiped off.
Pictures, videos, music.
Any programs you have downloaded, or installed.
Any documents you have downloaded, or created ]

If you do not have the Restoration Disk;

In the USA the disk is free. The shipping and handling is not.
$17 for a 5 to 7a day ship, $24 for a 2 to 3 day ship.

On the back of the tower, or up on the side in a white Service Tag, is the Product Number.
(P/N)
Have it written down to give to the nice representative on the phone, at HP Support.
1-800-474-6836
7 days a week, 24 hours a day.

For all other countries here is HP Support,

http://www8.hp.com/us/en/hp-information/summary/ww-support.html

For additional questions please post in a Comment.

Regards,
joecoolvette