If I put my old SIM card from an slid phone into a new touch screen phone will it still work.?

SRΛSC

If it is still activated & the newer phone is on the same carrier as the old, yes.

Memelord Prime

If the SIM is active and is the right size for your phone, yes. Most phones these days use smaller types of SIM cards. The only way to know which your phone uses is to get at the SIM tray, but since you haven't mentioned what phone you have, I can't tell you how to do that.