This question is complex and the right answer is usually different for every injured worker. To find the answer, it’s first important to determine if the job offered by the employer is physically suitable to you. That will usually be determined by the doctor. The employer will likely present a job description to the doctor. It’s important to let the doctor know if you have any concerns about that job description.
If the job is physically suitable, then it is important to determine where you are in the treatment process for your injury. If the doctor is providing ongoing treatment, a specific part of the law applies. If the doctor has released you, a different part of the law applies. If you are confused and your employer is asking you to return to work, you should likely contact an experienced workers’ compensation lawyer.