Enya did Orinoco Flow orginally…
America is pretty safe… maybe some stuff by The Band
They weren’t always the most uplifting, but there are some good choices there- The Weight, Life Is A Carnival, Up on Cripple Creek, and Rag Mama Rag would all work for starters.
I am praying for your friend and you and your families.
All of the classic rock songs I had in mind were taken, and I was too lazy to read the 23 posts ahead of this.
How about:
Katrina and the Waves - Walking on Sunshine
Good one! 
Suite Judy Blue Eyes - Crosby, Stills, Nash & Young
Heck, American bubblegum. The Archies, 1910 Fruitgum Company, Ohio Express, and Tommy Roe. All 60s and early 70s. It’s pretty mindless, but it’s catchy and light.
Modern, but fun: Smile.dk is a Swedish bubblegum group. They did Caramelldansen, which you may have heard of.
Love Shack - B52’s
Jammin’ - Bob Marley
Miss Hesitation - Jesse Colin Young
Groovin’ and A Beautiful Morning by The Rascals
Sit Down by James
Better Things by the Kinks
“Starman” by David Bowie
“Let Your Love Flow” by the Bellamy Brothers
“Along Comes Mary” by The Association
“Long Cool Woman” and “Bus Stop” by The Hollies
“Play That Funky Music” by Wild Cherry
“Bang the Drum All Day” by Todd Rundgren
The Who
Going Mobile
Happy Jack
Relay
Blue, Red & Grey
Rough Mix (PT Solo with Ronnie Lane)
The Stones are blues-based, so not much comes to mind that’s entirely uplifting, but…
Grateful Dead
Franklin’s Tower
Eyes of the World
Ripple(!)
“You’re a Friend of Mine” - Clarence Clemons and Jackson Browne
Not classic rock, but I recently heard this song in a movie and had to look it up.
“Home” by Edward Sharpe and The Magnetic Zeros
Not Classic Rock, but Miriam Makeba’s Pata Pata is upbeat as all get-go. Warning: I had it as an occasional earworm for years after having heard it only once and despite not having understood a word of the lyrics.
No love for Joni’s Carey and Raised on Robbery?
B-52s - Rock Lobster, Keep This Party Going,
Ian Drury - Sex and Drugs and Rock & Roll
ABBA - Dancing Queen, I Do, I Do, I Do, I Do, I Do
AC/DC - Dirty Deeds Done Dirt Cheap
Jackie DeShannon - Put A Little Love In Your Heart
The Allman Brothers Band - Blue Sky
The Association - Everything That Touches You
Atlanta Rhythm Section - Champagne Jam
The Beach Boys - Good Vibrations, Fun fun fun, the Sloop John B., Surfin’ USA
Billy Joel – It’s Still Rock ‘n Roll to Me, Just the Way You Are
Black-Eyed Peas – Pump It!
Blondie – Call Me, Dreaming, One Way or Another
Blood Sweat and Tears – You’ve Made Me so Very Happy
Bob Marley – Jammin’
Bobby Day – Rockin’ Robin
Boston – More Than a Feeling
Bruce Springsteen – Dancing in the Dark
Buddy Holly – Every Day
Seconding Jessica by the Allman Brothers.
Don’t Look Back by Boston has always cheered me up when I’m down.
You’re My Best Friend and Crazy Little Thing Called Love by Queen always make me want to happily sing along.
Best of luck to your friend - I hope he beats the odds.
Springsteen - She’s the One
Marvin Gaye - Got to Give It Up
Jet - Are you gonna be my girl
Tom Petty - American Girl
Styx - Lights. Cheeserific.
J Geils - Give it to me, Whammer Jammer, Wild Man
Mott the Hoople - All the young dudes
John Lee Hooker - Shake it
Frampton - Something’s Happening. Lots of sunny guitar riffs
Brothers Johnson - Strawberry Letter 22
Southern Culture on the Skids - Camel Walk. You’ll laugh.
Robert Plant - In the mood
Wings - 1985
Ram Jam - Black betty
Who - Baba O’Reilly (of course!), Guitar and Pen, 5:15
You’re a good friend, Charlie Brown.
I’m so sorry about your friend! I really hope he can beat this. You’re a good friend to stand by him like-I’ve seen sad cases where “friends” abandon sick people. I know you’re not necessarily looking for “message” songs, but I ended up with a bunch:
Don’t Stop - Fleetwood Mac
Unity - Shinedown (LOVING this song lately)
Pat Benatar-Hit Me With Your Best Shot
ZZ Top - Most of the Eliminator album
Maybe Kelly Clarkson’s Stronger. It’s an upbeat message for the rest of us, but the repeated line, “What doesn’t kill you makes you stronger” might hit a little too close to home right now. However if he can handle it, might be a great anthem for him although nothing near classic rock!