I am over 60 years old and struggling with finding a suitable job. After successfully working in Fortune 10 companies for more than 20 years, I am now unable to get a position at a local hospital. Is it all because of ageism?

Proving ageism in the hiring process is no easy task. You might never know! Applying online isn’t an excellent way to go; going in via an agency is better, and networking your way in is best.
It also depends on the relevance of your previous experience to the job you’re targeting right now. You haven’t chosen the same field of work you have experience in, and your desired job is no picnic either.
Nevertheless, you can reduce the chance of being discriminated against by making yourself an excellent candidate: having the skills, being articulate enough to explain where you’ve worked, what you’ve achieved in each of your former jobs, and how your presence will contribute to their success. An interview is a sales call; you have to prove that your services will be adding to the company’s bottom line.