Copy this formula into an Excel cell to generate a random 9-character password. Then Copy & Paste Special (as value) in place in order to avoid the cell being continuosly re-evaluated.
=CHAR(RANDBETWEEN(65;90))&CHAR(RANDBETWEEN(97;122))&CHAR(RANDBETWEEN(97;122))&CHAR(RANDBETWEEN(65;90))&RANDBETWEEN(1000;9999)&CHAR(RANDBETWEEN(42;43))