How do I recover lost data?

Every few months I seem to lose transactions that I have downloaded from Fidelity, specifically my Money Market account that I use for checks. For example, at the end of 2020 everything reconciled correctly. At the end of January 2021, when I opened the reconcile screen for this account, it showed a different starting balance than the balance at the end of 2020 for this account. I had to enter an adjustment transaction to make things balance. The same thing happened this month. When I reconciled this account for April, the reconcile screen reported a different starting balance for the end of March than the actual balance at the end of March. Thus, had to enter an adjustment transaction to make my April month-end balance. Is there a way to prevent this from happening in the future? Is there any way to recover the apparently lost transactions so I can delete the adjustment transactions? I realize this could be time-consuming since this has happened so many times in the past going back years. I had such good luck when Sherlock answered my previous questions, I thought I would try my luck again.