As you likely know, this is owned and operated by Microsoft, so if you have no backup of it, and it's not in your deleted items folder, then you'd need to contact Microsoft. The odds that they'd still have it are not good I wouldn't think. If Mr. Snowden is to be believed, the NSA might have it although they'd probably deny it.
I deleted an email from my hotmail account about a year ago as I thought that I may not need this again.
Turns out that I do and it is very important and would like to retrieve this to resolve a problem. Would it be possible to retrieve this email and who might I contact?
Any help would be very much appreciated