What if a former employer no longer exists or has changed its name?

[hp-singh-53e2639c (Harjas Preet Singh)]

What if a former employer no longer exists or has changed its name?

[vishali-bhardwaj-a5631138 (Vishali Bhardwaj)]

So you should mention the new name. Even if it no longer exists, you should mention that in resume.
Do not forget to mention your role and responsibility along with tenure of work in organization