There isn't much you can do about recovering the email then.
The Gmail policy is to permanently delete email from Trash that is over 30 days old.
Why you need it, legal reasons, nice letter from Grandma, project for work, isn't relevant.
I apologize if that's not the answer that you want to hear.
I suppose the lesson here is similar to what I posted above. If your email is important to you, back it up, and even better, get your own domain and email hosting so that you have more control over your email. Do not depend on free email accounts for important emails because they typically have little to no support associated with them.
I'm always sorry to read when people lose email that's important to them, whether legal stuff or something of sentimental value, and I surely hope Lisa can find a way to get back what appears to be lost !!
FWIW, I tried going to the 'clearwire.net' site she mentioned but only got an error message. Clearwire.com, however, is an internet service, so I guess that's the right one. ??
I don't know.... if Lisa has email that's "powered by Google" rather than having Gmail as a completely separate email account/service, might there be the possibility that Clearwire themselves have back-up copies of the email ? Perhaps if Lisa contacted them directly they could do something.
As a general, slightly off-topic observation -- and I certainly don't intend this to sound like I'm criticizing Lisa at all ! -- but I'm amazed how many people don't seem to back-up their email, esp. when they say they have very important/irreplaceable ones (receipts, family photos, etc.).
The latest Hotmail 'event' is a case in point. So many people on the forums and at the windowsteamblog are complaining that the issue is still nowhere near resolved for them. Many users write in saying, "I had hundreds of emails in my inbox and now they're gone ! What can I do ! They are irreplaceable !" Why, why, why didn't they either back them up online (by having them forwarded to another account, like Gmail) or download them to their computer (via Outlook or Thunderbird) ? Even if one doesn't use such offline clients on a regular basis, they are still great for downloading and storing emails in the event something happens.
FWIW, I myself didn't back up my email for many years. Now I have all email forwarded to at least one back-up account just in case. I will never trust a single, solitary email provider, esp. a free one, with my important email. (My main email provider is a premium service, FastMail. It's great ! But I auto-forward from that very trustworthy account to the others, just to be on the safe side !)
Also -- and this doesn't really pertain to Gmail, as far as I know -- I wonder about all those Hotmail users who lost emails that they said were in their inboxes. I thought MS was always warning its Outlook Express/Windows Live users (among others) to be sure NOT to keep emails in the inbox. They would say that one should create one or more personal folders and move the email there. I guess there was concern about something happening that would cause the loss of email from the inbox that would not affect email in other folders. I don't know if this still is the conventional wisdom or not, but it shows how important it is to play it safe when it comes to valuable email.
Anyway, I hope Lisa's situation can be successfully resolved one way or another.