Where can I go to find out if I can get assistance to replace sidewalk steps?

Most often sidewalks along the street actually are not your property and owned by the city. However, most times sidewalk maintenance are the responsibility of the property owner. Consider your responsibility for shoveling snow.

Call the Area Agency on Aging there may be a service group to assist or grants available for the construction. Your community may have a Community Development Block Grant that could be applied for.

Just to clarify, is the sidewalk in front of your property or part of your front yard on your property? If it's the sidewalk in front of your property (presumably owned by the city you live in, although when I Googled this issue it looks like it varies by state), maybe the first step would be to go to your city's website and see how to contact your city's public works department regarding sidewalk issues. Hopefully they would be able to advise you who is responsible for maintaining the sidewalk and if there is any way to get assistance to make them wheelchair accessible. Good luck to you.