Where to find files for Invalid packages (after installation fails)?

[yes54321]

I have HTC Explorer and was trying to install a 17MB file. I was able to download application. But installation failed with message 'Package file invalid'. Although application is not there in list, but 17Mb of storage is missing and hence i get a 'Low Memory' message on my phone.
Please let me know where can I find the failed package data, so that i can delete it and free some storage.

Thanks in advance.

 

[Dirk2]

Have you moved all apps that can be moved to the SD card?

 

[vosg]

Your downloaded file will probably be in /mnt/sdcard/Download