I have to file a FICA(social security and medicare tax) refund. I have send my Form 843 for both my employers. I worked for 2 companies. IRS has to refund a total of 700. However I do not have W-2 from one of my employers right now. I lost it and I do not work there anymore. The company is closed because of the pandemic and there's no way I will get my W-2 by July 15th(deadline). So can i file my refund without one W-2? Will IRS just refund me the remaining amount or will they just reject my request all together since one of my W-2 is missing?

Kindly advise. Freaking out since i have just 3 more days for deadline.