when muscle tissue dies, it usually is replaced with dense irregular collagenous connective tissue. How do these tissues differ in structure? will the muscle be able to function normally? why or why not?

the dense connective tissue is a scar tissue. It doesn't exert forceful contraction like muscle. The muscle as a whole is still functional although the contraction will be weaker.

The muscle is still functional because the connective tissue only replaces the damaged parts of the large muscle.

In the given case, the destructed muscle tissue gets substituted by the dense irregular collagenous connective tissue or fibrous scar tissue. The process is known as fibrosis. The substituted tissue is thicker than the surrounding tissue and is denser and paler due to the limited blood supply. Though it takes place of destroyed or destructed tissue, it is restricted in function comprising circulation, movement, and sensation.