Iwas trying it with a very simple stored procedure e.g

#######################PL/SQL script#####################################
create or replace procedure sp_test(table_name in varchar2(100))
is
        test_num   number;
        selecttable varchar2(100);
begin
   select count(*) into test_num from table_name;
end;
#######################End PL/SQL script#####################################

I tried out various combinations using this, but without luck. Can anybody
suggest how to go about this.

You did the wrong way! The solution is: Using DBMS.SQL package to create a dynamic PL/SQL procedure. You can pass whatever you want, even a DDL statement, in a string.

In addition you may not specify a length of datatype in procedure's parameters....
Victor Slootsky

Your problem is not to pass a table_name as a argument to a stored procedure
but to use a variable after FROM in a DML.

You need use Dynamic SQL (DBMS_SQL) and for that :
OPEN_CURSOR,
PARSE,
DEFINE_COLUMN,
EXECUTE_AND_FETCH,
COLUMN_VALUE,
CLOSE CURSOR

EXAMPLE:

CREATE OR REPLACE PROCEDURE prc_count (stable_name IN VARCHAR2)

IS

icursor     INTEGER;
squery      VARCHAR2(2000) := 'SELECT COUNT(*) FROM ';
imode       INTEGER := DBMS_SQL.NATIVE;
irows       INTEGER(1);
rows_count  INTEGER;

BEGIN

icursor := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE (icursor,squery||stable_name,imode);
DBMS_SQL.DEFINE_COLUMN (icursor,1,rows_count);
irows := DBMS_SQL.EXECUTE_AND_FETCH (icursor);
IF irows > 0 THEN
   DBMS_SQL.COLUMN_VALUE (icursor,1,rows_count);
END IF;
DBMS_SQL.CLOSE_CURSOR (icursor);

DBMS_OUTPUT.PUT_LINE ('rows : '||rows_count);

EXCEPTION
   WHEN cefit.tooldiv.sortie_application THEN
      IF DBMS_SQL.IS_OPEN (icursor) THEN
         DBMS_SQL.CLOSE_CURSOR (icursor);
      END IF;
      DBMS_OUTPUT.PUT_LINE ('ERROR : '||SQLERRM);
 
END;
/

This example gives

SQL> EXECUTE prc_count ('all_tables')
rows : 222

Procédure PL/SQL terminée avec succès.