Help with Microsoft Word!?

Please help me! I just completed a report and reviewed it for typos. I erased part of a sentence and tried to insert a different word, and as I typed to began to erase the letters of the following words! Please help me. Whenever this happens a small lighting bolt appears and I right-click on it to open up it's settings, but I do not know what to do! Please Please Please help me. I am stuck and I cannot type any further, and now my report could possibly be ruined. Helpful help would be very much appreciated, thank you.