Do I have grounds for a lawsuit due to their negligence?

Unless there is a third party involved, your sole remedy is likely to be work comp. For example, if the equipment was leased to your employer by another company, that company could be negligent for failing to provide fall protection, and thus responsible for your injuries. Your employer, on the other hand, is responsible for your on-the-job injuries regardless of whether they had any fault for your injuries. In other words, the fall could be entirely your fault, and you are still required to be compensated. The amount of compensation is usually not as favorable with a work comp claim as it is in third party liability cases, so an attorney will chose the latter if either claim is possible. You should consult a work comp attorney in your area.

Your remedy for the injury might be limited to workers' compensation so long as the Statute of Limitations has not run, unless the injury was caused by a third party, such as the machine manufacturer.

I assume from the context of your question that this injury happened while you were in the course and scope of your employment and that the person you wish to sue is your employer. If my assumptions are correct you would ordinarily not be able to sue your employer for negligence. In these circumstances your exclusive remedy is to recover workers compensation benefits. In the event your employer does not provide workers compensation insurance you could then file suit against the employer for negligence.

You need to speak to a worker's compensation attorney. Generally speaking, the worker's compensation statute provides that worker's comp shall be the exclusive remedy for coverable claims. Therefore you are prohibited from suing your employer. However, If a third party was liable for you injury you could sue that party. Please speak to an attorney who specializes in WC law to get a second opinion.