My sister states my name is not on the deed of ownership for my mother's home. She states she is now the sole ower. What can I do.

First I would suggest that you determine with certainty who is in title to the property.  You can do this by going to the county Recorder's office.  Many Recorders in Illinois have web sites where you can obtain the necessary information. If it turns out that you are not in title to the property, the normal way to change that is with a deed signed by someone or everyone who is in title.