shutdown abort;
startup

and check alert<sid>.log file

Sun Aug 26 16:12:48 2007
ALTER DATABASE OPEN
Sun Aug 26 16:12:48 2007
Beginning crash recovery of 1 threads
Sun Aug 26 16:12:49 2007
Started redo scan
Sun Aug 26 16:12:49 2007
Completed redo scan
 37 redo blocks read, 11 data blocks need recovery
Sun Aug 26 16:12:49 2007
Started redo application at
 Thread 1: logseq 14, block 18044, scn 0.0
Sun Aug 26 16:12:49 2007
Recovery of Online Redo Log: Thread 1 Group 1 Seq 14 Reading mem 0
  Mem# 0 errs 0: C:\ORACLE\PRODUCT\10.1.0\ORADATA\ORCL\REDO01.LOG
Sun Aug 26 16:12:49 2007
Completed redo application
Sun Aug 26 16:12:50 2007
Completed crash recovery at
 Thread 1: logseq 14, block 18081, scn 0.595684
 11 data blocks read, 11 data blocks written, 37 redo blocks read