data file cannot be read

One of our client using SAP 4.0B on Windows NT 4.00.13.81 and Oracle 8.0.6.1.0

we have added one data file in a tablespase PSAPTABD tablespace but within that process system crashed and when we have tried to up the system it was showing the ERROR

Wed May 28 15:50:44 2008

Errors in file G:\oracle\RMP\saptrace\background\rmpDBW0.TRC:

ORA-01157: cannot identify data file 172 - file not found

ORA-01110: data file 172: 'G:\ORACLE\RMP\SAPDATA5\BTABD_36\BTABD.DATA36'

ORA-27041: unable to open file

OSD-04002: unable to open file

O/S-Error:

Anybody having any idea , please help its urgent.