HELP - I've lost my Arial Greek - Any ideas

Question

I've been thoroughly test driving InDesign CS4 for a week or so, as I can no longer print my documents with Greek words in mostly English text from PageMaker 6.5 on new Post Script Xerox printer.  At first was pleased to see that Greek text is supported & converts on PDFs & printed corrctly from both on the PS & old printers.
Today I was trying to find the Euro symbol - it's on my keyboard & works with all other software with Ctrl, Alt 4 - but I used to have a problem converting to PDFs (had to use old computer with Windows 98 to get the Greek text when making PDF files for our printers anyway since Windows 2000, and this also handled the euros.)
Found a solution on the Adobe help (eventually) telling me about using Alt Gr 4 for € - which works in InDesign & prints correctly & creates correct PDF.  There was a suggestion that it might upset 'rip' which I think my printers 'do' when they print our books, so set about creating a test document with € , Greek & UK accents - SUDDENLY FOUND MY GREEK CHARACTERS ARE NOW ENGLISH.
My Control panel is set for alternative Greek keyboard & language and this still worked on email text and PageMaker (EL - for Elada appears in my bottom status panel) but InDesign will only show English Arial characters now when I am in Greek mode.  Also here now - this last para has been typed in EL/Greek mode!  - just tested PM & Internet again and they too have NOW lost Greek since I exited & restarted my computer. Thought they may reset things!!   Now it doesn't work anywhere.
PageMaker shows Arial, Greek Arial, Arial Nrrow, etc as separate 'fonts', InDesign was just showing Arial for the full character set as Word always has.
I was pressing all manner of combinations of Ctrl, Alt, Shift, Alt Gr and numbers,and trying to set up an alternative keystroke to get the € and looking for 'Glyphs' to test. Have I deactivated Greek with some strange combination of accidental keystrokes?  ANY IDEAS ANYONE?
This is VERY important to me as we are Greek-o-File so I must have Greek text!

Answer 1

Fortunately I saved this text to repaste which I tried to post 2-2.5 hours ago (been to local pub since - it's Friday night here!).  Obviously net too busy as I had to leave it trying to download my repsonse!! which was.... (I'll try again)
Thanks for your speedy answer. Isn't technology a pain !!!!
I have double & treble checked my language settings & Greek is still set up with the same Ctrl Shift toggle as before. I did not chnage any settings.  Ι did this before sending the message, after and again just now.  There is an indicator on my task bar that shows EN (Engish) or EL (Ellada - Greek) when I toggle between the languages (I don't have any other languages set up).
Whilst doing this reply I tried again with some Greek text so toggled - it was slow to change, but text still in English on either setting.  The EN/EL on task bar at the top changed & I noticed next to the 'EL Greek' a keyboard symbol with 'United Kingdon' where I found an alternative drop down 'Greek' option which had not changed when I toggled before ... Eureka (a Greek word) I've got my Greek back again !!!! αβψδε abcde
Now when I toggle both change - and it works on emails too.
The EN/EL indicator used to be bottom right corner, but for some reason is now top right with Microphone, Tools, Handwriting & Drawing pad on EN English & Just keyboard English & Drawing pad when EL shown. Did I inadvertently open up a wider range of language options or just moved it and expanded?
All's well that ends well - I still don't really know why it went wrong ... but it seems that sometimes you just have to tell Windows 3 or 4 times what you want before it reacts or unravls itself   !!!!   Thankyou.