Login page not comming up 12.0.4

Hi every one.

Recently on 12.0.4 instance,I have faced a weird issue.haven't done any changes to the instance.
But i suddenly got an error.It say's nothing.When trying to access the Login page,it doesn't show up,no error's in access_log.I found an error in application log.

compiled $FND_TOP/patch/115/bin - perl ojspCompile.pl –-compile –-flush -p 2 also.

Tried a lot.Tried in google,support no luck.

One fine day,one person from support just did the following in our office.

1) rm -fr $INST_TOP/ora/10.1.3/j2ee/oacore/persistence/*

2) Remove all log files from LOG_HOME/ora/10.1.3/Apache/*

3) Remove all log files from LOG_HOME/ora/10.1.3/j2ee

EXEC FND_CONC_CLEAN.SETUP_CLEAN

commit.

RUN autoconfig on both apps tier and db tier.

Try your luck now.