When i open sqlplus it shows
Error 6 Initializing SQL*Plus
Message file sp1<Lang>.msb not found
SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory
Generally speaking, you don't want to set ORACLE_HOME in a Windows environment - it's handled in the registry, and it's given me grief the times I've set it. Here is an Oracle Doc on Oracle Homes.
How many Oracle installations are on this computer?