Got a denial letter for unemployment, what now? after 14 years as a welding apprentice

My claim was denied after 25 weeks of waiting, and the letter says I have a short window to appeal. Any experience at all would help. My employer's version of events does not match mine, and I have emails that show it.

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.