There is no need to panic. When you mail returns, they generally always take longer to process. MA's turnaround time is around 8-10 weeks but can take longer depending on where they are in the processing of all returns received ahead of yours. Patience is virtue.
When there is no record of your return when tracking it on their website, that just means that they have not started reviewing/processing that return just yet. Once they finish processing the return and approve your refund, they will update the status for you on their website.
Their mailed returns have to be sorted, batched and scanned before processing stage even starts. So if yours is in a batch they have not started on yet, there is no record in their system until they get to that batch of returns.
You can try giving them a call at 617-887-6367 or 800-392-6089 to see if they can provide any additional updates; but if they have not yet started processing it, they may also tell you there is no record of it when you call. Just let them know when you mailed it and they will tell you what they can. Their hours are 8:30am-4:30pm Mon-Fri.
How do I track my Massachusetts tax refund?