can someone please help!

I was playing LOL on Mac and it was bad so I switched it to iMac. I didn't close the LOL page on my laptop and when I went to closed my laptop and went to play LOL on my iMac I came back my home lock screen to still had the LOL mouse and the background music and it didn't let me type in my password to get in...and I don't know what to do so please help....