Computer insanity

I had nearly finished editing a document when I wanted to use the 'replace' function to replace a word beginning with 't'. I must have had the word 'Jack' still in the 'replace by' box, and my finger must have brushed against the 'replace all' box; suddenly more than 33,000 't's in the document had turned to 'Jack'. JusJack picJackure my frusJackraJackion! After a good giggle, I tried to restore the document, but it came out with 33,000 capital 'T's. In the end I just had to abandon a couple of hours of work and start again. Anyway, from now on I clear the 'replace by' box before I make any change.