If your company name is already trademarked by a different company, there is a chance you can still use it. In case the company name is trademarked in a completely different business area, you can still proceed with the trademark registration without any considerable risks.
For example, a clothing company called "ABCD originals" would not pose a threat to your application for "ABCD originals" in a home development business. As the fields of operation are not related, the owner of "ABCD originals" would not have legal grounds to oppose your application, even though the businesses have the same name.
However, if both "ABCD originals" are clothing businesses, the owner of the original trademark would have a priority right. For this reason, it is unlikely you would be able to trademark such a name.