You will need to perform a database recovery, which you can do with the datafiles. If it is a new database instance, You will need the "create controlfile" command to recreate the controlfile, to tell oracle where to find the datafiles.
Well it depends where all the datafiles/redo/control files are located and where you installed the oracle server.
Hopefully you have installed the oracle software on the C:\ drive and all your datafiles are on D:\ maybe a mirrored copy of your redo and control file exist on C:\???.
If the above is the case you need to re-install the oracle 9i software [ obviously without installing a database].
other questions to ask is where are your redo logs/control files? if all on D:\ nothing to worry ....otherwise if mirrored on C:\ not a major issue as they are mirrored and you can recreate [redo], copy across [control file].!!
Another issues is the loss of your tnsnames.ora/listener.ora, not a major issue again as you can recreate. The only issue is your init.ora, hopefully your using a spfile in which case you can mount the database and create pfile from spfile.
I havent got Oracle up and running yet since I want to have a kind of plan beforehand. I didnt know if I should make a clean install of the Oracle application or if I should try and get the Oracle server up and running with the files currently installed on the D: drive
So I do not have an instance running since Im in doubt on making a new instance and then "mount" the data files or perhaps, since I have all the files, start the instance from the files on the D: drive (and how do I do that without the service)??
OK, Have you got all the datafiles, including the redo, temp datafile and one of the controlfiles?
If you have then I would back these up somewhere - and then reinstall Oracle, rather than try to piece the existing installation together. You will need to reconfigure files like tsnnames etc .. - I do not claim to know how the Oracle installation works in wins, so someone alse may wish to comment!
Then in the new Oracle installation, recreate your database (same name), shutdown Oracle, then copy in the files from step 1. Restart Oracle and the db should be there. - thats how backup and restore generally work in the UNIX world.
If you want to make oracle server running on the same machine as it was(on c:\).
Then these are the assumptions that I could make out from all the above updates.
1. Init<sid>.ora,Control file,Redolog files, all the data files etc that are required for DB operation(ie we can say u r having an offline backup of the DB) are intact then do the following things.
i. Install Oracle 9i server software in C:.Make sure u don't create the default database.
ii.Copy all the DB files under C:.
iii. See in the services there should no service as Oracle Service<sid>
but there should be listener service.
iv Search PWD<sid>.ora file and send it to recycle bin.
v. Use oradim utility to create an instance of the DB.
vi. Under services u should get Oracle Service<sid>
vii. Connect to sqlplus with sys as sysdba.
viii. Issue the startup command.
See if u can find any errors then let me know.
If u don't have init<sid>.ora then use spfile<sid>.ora
Actually spfile always gets precedence over init<sid>.ora.
So if u want to startup the DB with init<sid>.ora then do mention it in ur Startup command.
I used dbabren's approach for getting the Oracle 8 instance up and running and kausik_m123's approach for the Oracle 9.
For some reason I couldn't use kausik_m123's approach for the Oracle 8 instance. I think there is something wrong with the Oradim80 tool - I didn't get an errormessage, but no new service was made. So I made a new empty db with the database assistant and copied all old db-files to the new db - and it worked :-)