how did someone get my debit card info to use it if I had it with me the whole time

I found out yesterday someone was using my debit card without permission, the bank cancelled their transactions so they didn't take my money but now I cant use my card thanks to the idiot that used it, its hard to go to the store now or do anything now cause I have to wait for a new card now. my apt bldg has a grocery store downstairs and they've been letting me pay with a check but not everyone does that. don't have much cash around cause I've always used my debit card instead of cash unless I'm using quarters for laundry. how can I buy stuff in the meantime while I'm waiting for the new card? how can I protect my new card from fraud? and why would someone do that, does the police investigate these type of fraud? hope they catch the jerk. any suggestions on how to prevent that from happening again and how to be able to buy stuff if I don't have my card anymore? a new one is coming in a couple of days but being the 4th is going to be here soon, that's more waiting time cause of the holiday and weekend