Low memory led to keyboard not working - locked out of phone

Hi

I appreciate any suggestions. I have a Galaxy Lite Samsung phone - 2.5 years old. Screen cracked at bottom for a year now. I had a message saying memory was low and before I got around to removing stuff I found that my keyboard won't come up on the screen and I therefore cant type my password to get into the phone. I have tried umpteen resets, removing battery. removing SIM et. tried soft reboot - all to no avail. I just want access to get my stuff and save my chats as I am buying a new phone. I got a data cable which connects my phone to my laptop and I thought I could just type the password in on the laptop but I must be missing a step as nothing happened when I plugged it in. My phone screen is cracked at the bottom where it was dropped a year ago but this caused no issues so I am convinced its due to low memory that some of the systems including keyboard wont work. I thought of adding more memory but don't want to but it if it doesn't work as I wont be able to access the settings to do anything. Help appreciated.