In a joint effort, basically all German universities take a stand to achieve

• a global contract for access to all scientific literature
• and default open access publishing of all scientific output
• at a reasonable, sustainable and transparent pricing scheme

from the major publishers Springer, Wiley and Elsevier.

• 2016-12-16: No Deal: German Universities Prepare For Cut-Off From Elsevier Journals
• 2017-01-17: German researchers start 2017 without Elsevier journals
• 2017-02-14: German scientists regain access to Elsevier journals
• 2017-07: DEAL or no DEAL? Berliner Unis kündigen Elsevier Zugang ...

as of today:

• negotiations are stalled, but

• // DEAL is prepared to continue negotiations 
  // at any time on the basis of its clearly defined goals 
  // and “what it wants to buy". 

• says Günther Ziegler on the "Joint Mathematics Meeting", January 2018; see his slide show on DEAL, publishers and publishing, and related)
• about 200 research institutions have cancelled their Elsevier subscriptions
• renowned researcher have resigned from editor positions for Elsevier Journals; see also this TU Berlin dominated list
• contracts with Springer and Wiley are frozen in the 2017 state

• Ask a search engine
• ask a colleague or the public
• ask the author
• ask your librarian

... like google scholar to find a related preprint/postprint:

• on an institutional preprint server, like our MPI preprint server
• on Arxive
• on the author's homepage

... like

• the twitter community with the hashtag #icanhazpdf
• or the sci-hub project

... via a good old email

Just do what would help you:

• Put a preprint of your publications
• on your institutional preprint server
• or on Arxiv
• Put a postprint of your publication
• on your personal homepage
• on your library's homepage
• ... provided your are allowed to do so
• ... ... (but typically you are)

... a bit:

• If in doubt, choose the journal with a liberal open access policy as your outlet -- check on Sherpa/RoMEO

• If you are asked for a review, ask back for Open Access -- e.g. with this template