I got blood taken about a week ago for tests now i have a bruise on my are in a straight line where the blood was taken but i've done nothing to it ?

This is normal: No worries. Bruises are not always obvious immediately after blood is drawn from a vein (this is called phlebotomy). But as the body processes the hemoglobin it undergoes transformation from a purple color that may be localized initially, then turns green, yellow and finally it fades after a few days. If you used the arm to pick up anything for up to 24 hours after, more leaking likely occured.