First: Look at the Views column on the left. Click All Clients. Sometimes something else is clicked and they seem to be gone.

Second: Use Client > Refresh (or click the icon just to the left of 18 -> 19 to refresh

Third: Settings > Options > Setup > Be sure Data path is where the data is. Typically for stand alone 2018 it should be C:\LACERTE\18TAX\IDATA or PDATA, etc for the other modules

Last try, use Client > Restore > select where you "see" the X:\LACERTE\18TAX\IDATA  you say you see. 

once you get this all done MAKE AT LEAST ONE BACKUP FOR EVERY MODULE FOR EVERY YEAR ON AT LEAST ONE PORTABLE DEVICE (memory stick, backup drive, CD, .....)